AGRICULTURAL 



QUALITATrVE AND QUANTITATIVE 



CHEMICAL ANALYSIS, 



'^i^i^ 



E. WOLFF, FRESENIUS, KROCKER, AND OTHERS. 



EDITED BY 



G. C. CALDWELL, 

M 

PKOFESSOR OP AGEICULTTJKAL CHEJOSTKY IN THE COBKELL TTNTVEKSITT. 




NEW YORK: 
ORANGE JUDD AISTD COMPANY, 

245 BROADWAY. 

/ 



Entered according to Act of Congress, in the year 1869, by 
ORANGE JUDD & CO., 

In the Clerk's Office of the District Court of the United States for the Southern 
District of New York. 



'0-' i- 



PREFACE. 



The purpose of this work is to supply a complete 
manual of chemical analysis, for the use, especially, of 
agricultural students. 

The qualitative and quantitative processes that are de- 
scribed refer only to such substances as are found in soils, 
plants, animals, fertilizers, or other materials or products 
of agriculture ; and, moreover, in order to reduce the size, 
and consequently the cost of the book as much as possi- 
ble, excejDt in two or three instances, only those methods 
of analysis are introduced which are most commonly 
used by good chemists, and have been tried and found 
reliable, with such improvements as have been made in 
more recent practice. 

The chapters on Special Analyses consist, in the main, 
of a translation of the " Anleitung zw Chemischen Jln- 
tersuchung landwlrthschaftlich-wichtlger Stoffe^ von Dr. 
Bmil Wolff, 2te Avflage, 1867," a work of the first au- 
thority in Germany ; two or three unimportant matters 
have been omitted, the arrangement has been somewhat 
altered, and some additions have been made to the original. 

The other chapters, on reagents, manipulation, etc., are 
3 



IV PREFACE. 

made up largely from the " Anleitung zur Quantitatlven 
Chemischeji Analyse^ von Dr. C. B. Fresenias^ 6te 
Auflage, 1866." 

Concerning late improvements in methods of analysis, 
the Zeitschrift filr Analytische Chemie, by the same au- 
thority, has been frequently consulted. 

The scheme of qualitative analysis has worked well in 
my own hands, and with my own students, but, neverthe- 
less, I would have preferred to give it a more careful 
trial before publishing it. 

Valuable assistance in testing this and other methods 
of analysis has been received from Mr. T. B. Comstock, 
while a student in my laboratory. 

The use of the old system of atomic weights, and of 
the old nomenclature, would doubtless have made the 
book more simple to the majority of students at first, but, 
nevertheless, it seemed more expedient to follow the com- 
mon usage in the best recent works on chemistry. The 
same may be said in regard to the use of the centigrade 
thermometer and the metric system of Aveights and 
measures. 

Although the work has been somewhat hastily prepared 
to meet a pressing want in my own laboratory, I trust it 
may yet be found to answer a good purpose in other lab- 
oratories where agricultural chemistry is made a specialty. 

G. C. C. 

Cornell University, College of ] 
Agriculture, August, 1869. f 



TABLE OF CONTENTS. 



CHAPTER I.— Tlie Reag-ents. 

List of the reagents needed, with directions for preparing tliem, when 
not more readily obtained otherwise, and for testing their purity. 7 

CHAPTER II.— Analytical Manipailatioii. 

Determination of specific gravity, solution, evaporation, precipita- 
tion, filtration (Including Buusen's new method), weighing of 
residues and preci[ntates, measuring and dividing solutions, and 
calculation of results 23 

CHAPTER III.— Reactions and jrictlioels oi' ^^nantita- 
tive fHi^tiniation. 

Potassium, sodium, ammonium, barium, calcium, magnesium, alumin- 
ium, iron, manganese, zinc, lead, copper, and arsenic; silicic, 
sulphuric, carbonic, pliosplipric, nitric, hydrochloric, liydrocyanic, 
hydroferrocyanlc, hydrosulphuric, hydriodic, hydrofluoric; oxalic, 
acetic, tartaric, citric, malic, lactic, uric, hlppuric, and tannic 
acids ; cellulose, starch, gum, the sugars, albuminoids, urea, fat, 
and alcohol 44 

CHAPTER IV.— J^pecial Metliodi^ of Analysis. 

Course of qualitative analysis, estimation of water, of organic mat- 
ter, of sulphur and chlorine in organic compounds, special 
methods of separation of bases and acids, schemes of analysis. . .128 

CHAPTER v.— Analysis of ^oils and ]loel«:s. 

Mechanical and chemical analysis, and examination of physical prop- 
erties, of soils, and examination of marl, limestone, and cla}- 165 



VI TABLE OF CONTENTS. 

CHAPTER VI.— Fertilizers. 

Farm-yard manure, urine, solid excrements, bone-meal, bone black, 
bone-asb, pbospborite, guano, superphospbate, gypsum, salt, 
potash compounds, and Chili saltpetre 313 

. CHAPTER VII.— Aslies. 
Ashes of plants, of animal substances, and of fuel 241 

CHAPTER VIIL— rodder and Food. 

Fodder plants, beets, turnips, potatoes, seeds, meal, flour, milk, 
butter, cheese, and vinegar 251 

CHAPTER IX.— Wool and Bark. 

Examination of wool and tanners' baric 269 

• CHAPTER X.— Beverages. 

Water and wine 271 

CHAPTER XI.— Tables. 

Metric system of -weights and measures, atomic weights of elements, 
factors for calculating analyses, estimation of tannin in bark, etc.284 



AGRIC ULTURAL 

QUALITATIVE AND QUANTITATIVE 

CHEMICAL ANALYSIS. 



CHAPTER I. 

REAGENTS. 

The following list contains all the reagents used in the 
various courses of analysis described in this book, arranged 
in alphabetical order. Most of them can be procured of 
the druggists, or the dealers in apparatus and chemicals. 

Directions are given here for the preparation of such 
reagents only as cannot be thus obtained conveniently. 
The chemical tests to which each reagent should be sub- 
jected, in order that the analyst may be assured of its 
purity, and the strength of the solutions to be made, are 
also given, wlien it is necessary. Most of this information 
is taken from the works of Fresenius. 

The new system of nomenclature and the new formulas 
being adopted in this work, the new name and formula 
of each reagent are given first, and, for the benefit of 
those who are less familiar with these, the old name and 
formula are afterwards enclosed in parentheses, whenever 
there is any essential diiFerence between the new and the 
old. 

7 



8 § 1. EEAGENTS. 

1. a.— Acid, acetic— HC,H30,. (HO,C,H303. HO,a.) 

— This should leave no residue on evaporation, and 
should emit no empyreumatic odor when evaporated after 
saturation with sodic carbonate ; neither hydrosulphuric 
acid, argentic nitrate, nor baric chloride should produce 
any change in it, nor amnionic sulphide, after neutraliza- 
tion with ammonia. 

h. Acid, citric— H3CJI,0,. (3HO,C3^H,0,,.)— l^ecrys- 
tallize it, unless clean and colorless. 

c. Acid, liydrochloric — HCl. (Chlorhydric acid. Mu 
riatic acid.) — This must be colorless, and it should leave 
no residue when evaporated on platinum foil, nor should 
it attack the foil ; it should give no blue color to starch- 
paper, nor should it bleach starch that has been faintly 
colored blue with iodine ; it should give no turbidity with 
baric chloride, after having been considerably diluted, nor 
should it be colored by hydrosulphuric acid or potassic 
sulphocyanate. 

For the dilute acid, add the concentrated acid to 4 parts 
of water. 

d. Acid, hydrosulpliuric — H^S. (HS.) — Pour dilute 
sulphuric acid through a funnel tube over fused ferrous 
sulphide, in a common bottle, and conduct the gas that is 
evolved, first through water in a small wash-bottle, and 
then into distilled water. The solution should emit a 
strong odor of sulj^huretted hydrogen, and should be 
freshly made. 

e. Acid, nitric— H]sr03. (HO,NO,.)— This should be 
colorless, and should leave no residue when evaporated on 
platinum foil ; after having been considerably diluted, it 
should not be made turbid by argentic nitrate or baric 
chloride. For the dilute acid, add the concentrated acid 
to 4 parts of water. 

/. Acid, nitro-hydrochloric Aqua regia.— Mix to- 
gether 1 part of pure nitric acid, and 3 or 4 parts of pure 
hydrochloric acid. 



§ 1. REAGENTS. 9 

g. Acid, oxalic— H^C^O,. (2H0,Cp,.) This should 
not present the least appearance of efflorescence ; it 
should give a perfectly clear solution with water, and 
sliould leave no residue when ignited in a platinum dish. 
If the^acid does not meet these requirements, it should be 
purified by repeated recrystallization. 

Stolba (Fresenius^ Zeitschrift 8, 63) recommends subli- 
mation as a convenient method of purifying oxalic acid. 

Dry the acid thoroughly by keeping it in a warm place 
for a considerable time, with occasional stirring ; when a 
small portion of it, gently heated in a test tube, gives off 
but little water before subliming, it is sufficiently dry. 
Put it, then, in a large beaker to the depth of 15-20 mm., 
cover the beaker Avith a hollow cone of paper, and im- 
bed it in iron turnings in an iron dish, to the same depth 
as that of the acid inside, and heat it cautiously, raising 
the temperature very gradually. Scrape off the outside 
of the cone of sublimed acid, sei3arate the more solid yel- 
lowish outer part from the white inner portion, and purily 
each by itself by crystallization from solution as usual. 

h. Acid, sulphuric. — H^SO^. (H0,S03). — Common 
sulphuric acid usually contains lead, which is precipitated 
as a fine ^^hite powder, when the acid is diluted with con- 
siderable water, or when mixed with 4 or 5 parts of 
alcohol ; it sometimes gives a red color with a solution of 
ferrous sulphate, where the two liquids come in contact (§ 
62), and, w^hen diluted, gives the reaction for chlorine with 
argentic nitrate (§ 63), and for arsenic by Marsh's test 
(§ 57). The j^ure acid should give none of these reac- 
tions, nor any blue color after dilution with 20 parts of 
water, when a little starch paste and potassic iodide are 
added to the cooled liquid ; it should be volatilized com- 
pletely when heated. 

The dilute acid is prepared by adding the concentrated 
acid to 5 parts of water, slowly, and with constant stir- 
ring, letting the mixture stand a lonix time if any plumbic 
1* ^ 



10 § 2. REAGENTS. 

sulphate is precipitated, and then decanting the clear su- 
pernatant liquid for use. 

^. Acid, silicic— See Quartz. 

h. Acid, tanilic, needs no testing. 

2. Alcohol.— C^H^O. (C^H^,.)— This is used both in 
its pure state (absolute alcohol), and mixed with water 
until its specific gravity is 0.83 or 0.84, corresponding 
to about 90° I g of pure alcohol, by volume. 

It should be volatilized completely, and leave no odor 
of fusel oil when rubbed between the hands ; it should 
burn with a pale blue, barely visible flame, and should 
not redden blue litmus-paper. 

3. a.— Ammonic acetate— NH^C.HgO^. (Acetate of 
ammonia. NHp,C^H303. NH,0,A.)— This should be 
colorless, free from empyreumatic odor, and inorganic 
acids, and should be completely volatilized when heated. 

h. Amnionic carbonate.— (NH J „C03. (Carbonate of 
ammonia. NH40,C02.) — This should be completely 
volatilized when heated, and, after supersaturation with 
nitric acid and heating, should give no reaction with solu- 
tions of silver, barium, or ammonic sulphide. Dissolve it 
in 4 parts of water, and add 1 part of ammonia. Keep 
some of the salt also in the dry form. 

c. Ammonic chloride. — ^NH^Cl. (Chloride of ammo- 
nium.) — ^This should be completely volatilized when heated 
on platinum foil, and should give no reaction with am- 
monic sulphide, baric chloride, or litmus. Dissolve in 8 
parts of water. Keep some of the salt also in the form 
of a dry powder. 

d. Ammonic fluoride.— NH^F. (Fluoride of ammonium.) 
— This, when heated in a platinum dish, should leave no 
residue; if impure, it may be purified by sublimation 
between two platinum dishes. It should be kept in gutta 
percha bottles. 



§ 3. KE AGENTS. 11 

e, Ammonic hydrate.— NH^HO. Ammonia JSFir^.— 
This should be colorless, and leave no residue -when evap- 
orated in a Tvatch-glass : after dilution with its volume of 
water, it should give no very marked turbidity with lime- 
water, and, after supersaturation with nitric acid in slight 
excess, it should give no precipitate or color Avith argentic 
nitrate, baric chloride, or ammonic sulphide. 

/. Ammonic molybdate. — (NHJ^MoO,. (Molybdate 

of ammonia. NH^OjMoOg.) — Dissolve 1 part of molyb- 
dic acid in 8 parts of ammonia-water, pour the solution 
into 20 parts by weight of nitric acid (Sp. Gr.=1.2), let 
the mixture stand several days in a warm place, and 
decant the clear liquid for use. When moderately heated 
with excess of nitric acid, it should give no yellow pre- 
cipitate. 

g, Ammonic nitrate. — ISrH^N"03. (^^itratc of ammonia. 
NII^O, NO^.) — This should give no reaction with baric 
chloride or argentic nitrate, and should be completely 
volatilized when heated. 

A. Ammonic oxalate.— (NH J ^C^O^. (Oxalate of am- 
monia. 2NI-I^O,C40g.) — This should be completely vola- 
tilized by heat, and should give no reaction with hydro- 
sulphuric acid, or ammonic sulphide, or with baric chloride 
in a solution acidified with hydrochloric acid. Dissolve 
in 24 parts of water. 

i. Ammonic sulphate. — (XIIJ^SO^. (Sulphate of am- 
monia. KH^OjSOg.) — This may be readily j^repared by 
neutralizing ammonic hydrate Avith dilute sulphuric acid. 

Jc. Ammonic Sulphide. — (NHJ^S. (Sulphide of am- 
monium. KH^S.) — -Conduct sulphuretted hydrogen (§ 1, 
cl) into 3 j^arts of ammonic hydrate as long as the gas 
is absorbed, and add 2 parts of fresh ammonic hydrate. 
The reagent should evolve sulphuretted hydrogen freely 
when mixed with strong acids, and should give at least 
only a white precipitate with them ; it should give no re- 



12 



KEAGENTS. 



action at all with solutions of lime or magnesia ; when 
evaporated in a platinum dish, the residue should be vola- 
tilized completely on ignition. 

Dissolve some flowers of sulphur in a small portion of 
the reagent, and label tliis solution, ammonic sulphide 
vnth excess of sulphur, 

I Ammonic tartrate.— (^H J, C^H^^. (Tartrate of 
ammonia. 2iSrH O,CJT0,„.) — Neutralize tartaric acid 
with ammonic hydrate, and then add more ammonic hy- 
drate, so that it shall be in excess over the acid. 

m. Ammonic-fcrrous sulphate. — (NHJ„Fe (SOJ^. 
(Sulphate of protoxide of iron and ammonia. NH^O, 
FeO, (SOg)^.) — Divide a quantity of sulphuric acid into 
two equal parts ; heat one of them with an excess of 
small clean iron nails free from rust, as long as the evolu- 
tion of hydrogen continues. Neutralize the other portion 
of the acid accurately with ammonic carbonate, and then 
add a fevf drops of sulphuric acid. Filter the solution of 
ferrous sulphate, obtained by the action of the acid on the 
nails, into the amnionic sulphate, evaporate the mixture 
a little if necessary, and let it crystallize. Let the crys- 
tals drain in a funnel, dry them by exposure to the air on 
filter-paper, and keep them in a well stoppered bottle. 
The solution of the salt in water acidified with sulphuric 
acid should give no red color with potassic sulphocyanate. 

4. Argentic nitrate. — AglSTO^. (Nitrate of silver. 

AgO, NO^.) — ^After the solution of this reagent has been 
completely precipitated with hydrochloric acid, the fil- 
trate from the precipitate should leave no residue Avhen 
evaporated, and the same filtrate should give no color 
with ammonic sulphide. Dissolve in 20 j^arts of water. 
All the silver refuse, consisting of ^precipitates contain- 
ing silver, and solutions to which argentic nitrate has been 
added, should be tlirown into a bottle containing dilute 
hvdrochloric acid. When a sufficient quantity of the 



§ 5. KEAGENTS. 13 

precipitated chloride has accumulated, separate it from 
the liquid by decantation of the latter, wash it Avell with 
water, pour dilute sulphuric acid over it, and put some 
jiieces of zinc in contact with it. 

When the whole is changed to a gray metallic powder, 
and the zinc is all dissolved, filter out and wash the pow- 
der well, dry, and ignite it. Dissolve the silver thus ob- 
tained in nitric acid, add Avater, filter if necessary, evap- 
orate the filtrate to dryness on the water-bath, and dis- 
solve the residue in 20 parts of water, and subject the 
solution to the tests above described. 

5. r^— Baric acetate. — Ba(C„H30j2. Acetate of 
baryta. BaO,C ^1303. BaO,A.)— This should be colorless 
and should have no ompyreumatic odor, and it should 
give no reaction with amnionic sulphide or argentic ni- 
trate ; after complete jirccipitation witli sulphuric acid, 
the filtrate should leave no residue on evaporation. Dis- 
solve in 10 parts of water. 

h. Baric chloride. — BaCl„. (Chloride of barium. BaCl.) 
—This should not affect litmus-paper, nor give any 
reaction with ammonic sulphide ; after complete pre- 
cipitation with sulphuric acid, the filtrate from the precipi- 
tate should leave no residue when evaporated. Dissolve 
in 10 parts of water. 

c. Baric hydrate. — Ba(nO)„. (Hydrate of baryta. 
Baryta water. BaO,HO.) — After precipitation of the 
barium from the solution by sulphuric acid, the filtrate 
should remain clear when mixed with alcohol, and should 
leave no residue when evaporated. Dissolve in 20 parts 
of water. In determinations of urea in urine, a mixture 
of one volume of a cold saturated solution of baric nitrate 
and two volumes of a cold saturated solution of baric 
hydrate is used. 

d. Baric nitrate.— Ba(N03),. (Nitrate of baryta. BaO, 
NO J.) — This should be completely precipitated by sul- 



14 § 6. REAGENTS. 

phiiric acid so that the filtrate from the precipitate leaves 
no residue when evaporated, and it should give no reac- 
tion with argentic nitrate. 

e. Calcic chloride. — CaCl^. (Chloride of calcium. CaCl.) 
— This should not afl'ect litmus-paper, should give no 
reaction with ammonic sulphide, nor any ammonia when 
heated with sodic hydrate. Dissolve the crystals in 5 
parts of water. 

The crude, imjmre, fused chloride answers for desicca- 
ting purposes. 

/. Calcic fluoride. — CaF„. Fluor sx>ar. — To ^ave 
trouble, buy the poicdered fluor spar. 

g. Calcic hydrate. — Ca(H0)2. Lime-water. (CaO, 
HO.) — Digest slaked lime with cold water with occasional 
stirring, let the mixture stand quietly for a time, and de- 
cant the clear liquid for use. It should give a dark color 
to turmeric-paper, and a considerable precipitate with 
ammonic oxalate. 

For many purposes milk of lime is used in preference 
to lime-water ; this reagent is simply lime-water mixed 
with an excess of undissolved calcic hydrate. It should 
be made with lime from white marble, and should be kept 
in well stoppered bottles, and shaken up 'when used. 

A. Calcic sulphate.— CaSO^. (Sulphate of lime. CaO, 
SOg.) — Digest j)owdered, crystallized gypsum a long time 
with cold water, with frequent agitation, let the mixture 
stand quietly at last, and decant the clear liquid for use. 

6. Chlorine. — CI. — Nearly fill a flask vrith manganic 
binoxide in pieces about as big as peas, and then add so 
much common, concentrated hydrochloric acid, that about 
half the oxide will be immersed in it. Conduct the gas, 
by a glass tube passing through the cork with which the 
mouth of the flask is closed, through a cylinder or wash- 
bottle containing concentrated sulphuric acid. The evo- 



§ 7. r.E AGENTS. 15 

lution of the chlorine begins at common temperatures, but 
a little heat must be applied after a time. 

7. Cobaltic nitrate.— Co(NO„)._^.— Dissolve the salt in 
10 parts of water. 

8. Cochineal solution.— Boil cocliineal with welter. 
The solution will keep better if about half its volume of 
alcohol is added to it. 

9. «.— Cupric acetate. — Cu (CJIgOJCuO. (Acetate 

of copper. Verdigris. 2CuO,CJl303.) — To prepare the 
solution of this salt for washing the precipitate of baric 
sulphate, dissolve the commercial salt in water contain- 
ing a liltle acetic acid, add 2 drops of sulphuric acid, if 
this acid is not already present, then a few drops of baric 
chloride until the liquid gives a faint reaction for barium, 
boil a short time, and filter. The solution should be suffi- 
ciently concentrated to deposit crystals on cooling. Use 
the supernatant saturated solution. 

h. Cupric sulphate. — CuSO^. (Sulphate of copper. 
CuO,S03.) — This should be recrystallized once or twice. 

10. Curcuma-paper. — Turmeric-paper. — Digest pul- 
verized curcuma root with 6 parts of weak alcohol, color 
slips of unsized paj)er wdth the yellow extract, and dry 
them. 

11. Ether.— CJI,„0. (C^RO.)— Tl>is is sufficiently 
pure as obtained of the druggist. 

12. a. — Ferric chloride. — Fe^Cl^ (Perchloride of iron. 
Fe^Clg.) — Its solution should give a 2)ermanent precipi- 
tate with a drop or two of ammonic hydrate ; it should 
give no blue color with potassic ferricyanide. Dissolve in 
20 parts of water. 

h. Ferric oxide. — Fe^O^. (Sesquioxide of iron.) — This 
is also known as colcothar. 

c. Ferric nitrate. — Fe(N03)„. (Nitrate of sesquiox- 
ide of iron. Fe203,3N'Oj.) — Dissolve iron in nitric acid, 



16 § 13. IIEAGENTS. 

evaporate the solution to expel excess of acid, and dis- 
solve the residue in 10 parts of water. 

d. Ferrous chloride. — FeCl„. (Protochloride of iron. 
FeCl.) — Dissolve j^ianoforte wire in concentrated hydro- 
cliloric acid ; the solution should be made as it is wanted. 

e. Ferrous sulphide. — FeS. (Sulphide of iron.) — Get 
the fused sulphide of the druggists. 

13. Hydrogen. — H. — This is made by the action of di- 
lute sulphuric acid on granulated zinc. To purify the gas 
conduct it through a U tube, or a calcic-chloride cylinder, 
containing freshly ignited charcoal, and in order to dry 
it, through another cylinder containing calcic chloride. 

14. Indigo solution. — This may be prepared by treat- 
ing 1 part of finely powdered indigo with 5 parts of 
fuming sulphuric acid 48 hours in the cold, and pouring 
the mixture into 20 parts of cold Avater. 

15. Iodine* — I. — This needs no testing. 

16. a. — Iron Turnings. — These should be clean and 
free from grease. 

h. Iron wire. — Get the finest pianoforte wire, free from 
rust. 

17. a. — Lead-paper. — Soak slips of unsized paper in a 
solution of j^lumbic acetate, dry, and keep in a well stop- 
pered bottle. 

h. Litmus-paper (blue). — Digest litmus with G parts of 
water, filter, divide half of the filtrate into two equal 
parts and carefully saturate the free alkali in one of those 
parts with sulphuric acid, until the liquid has taken a red 
color that does not disappear after standing a few min- 
utes ; add the other part to this, color strips of unsized 
paper in the blue liquid, dry them, and keep in a dark 
place. The strips should have a blue color. 

c. Litmus-paper (red). — Add sulphuric acid to the 
other half of the extract of the litmus until a permanent 



§ 18. liE AGENTS. 17 

red color is just obtained ; color slips of unsized paper in 
this solution, dry them, and keep in a dark place. The 
strips should have a distinct red color. 

18. a. — ]>Iagnesia (calcined).— MgO. — ^This should be 
freshly ignited before being used. 

h. Magnesia mixture. — ^IMix together 1 part of mng- 
nesic sulphate, MgSO^, 1 of amnionic chloride, 4 of am- 
monic hydrate, and 8 of water; let the mixture stand 
several days in a moderately warm place, and decant the 
clear solution for use. 

19. Malt. — Get good brewer's malt. 

20. Manganic binoxide. — MnO„. — The commercial, na- 
tive, crystallized hlnoxide of manganese is generally suf- 
ficiently pure. 

21. «.— Mercuric nitrate.-— Hg(N03)„_. (Xitrate of 
mercury. HgO,NO^.) — Dissolve mercury in its own 
weight of nitric acid (Sp. Gr. = 1.4), heat the mixture to- 
wards the close of the operation, and, finally, add to it 
twice its bulk of water. 

h. Mercurous nitrate.— Hg,(]Sr03) 2. — (Subnitratc of 
mercury. HgoO, KO^.) — ^Pour 1 i^art of pure nitric acid 
(Sp. Gr. =1.2) over 1 part of mercury, let stand 24 hours 
in a cool place, separate the crystals from the undissolved 
mercury and the mother-liquor, dissolve them in water 
mixed with ^1^^ of nitric acid, by trituration in a mortar, 
filter, and keep the solution in a bottle with metallic mer- 
cury covering the bottom. 

MicrocOSmic salt. — Seesodlc ammGnlc pTiospTiate. 

Milk of lime. — See calcic hydrate. 

22. Oxygen, — O. — Mix1;ogether in a mortar 100 grras. 
of potassic chlorate and 0.1 grm. of ferric oxide, half fill 
a retort with the mixture, and heat over a coal fire, at first 
gently. As soon as the contents of the retort are partly 
fused, mix them together by gentle agitation. Collect 



18 § 23. keagejStts. 

the gas ill the gasometer; for use, conduct it from the 
gasometer through a solution of caustic potash (Sp. Gr.= 
1.27) in a Liebig's potassa-bulb, then through a U tube 
containing pumice-stone soaked in sulphuric acid, and 
finally through a tube containing calcic chloride. 

Phosphorus salt. — See sodlc ammonic phosphate. 

23. Platinic chloride.— PtCl^. (Bichloride of plat- 
inum. PtCl^.)— Its solution, evaporated to dryness on 
the water-bath, should leave a residue entirely soluble in 
alcohol. 

Precipitates and solutions containing platinum should 
be thrown into a bottle containing a solution of ammonic 
chloride. "When a suiticient quantity of the precipitate 
has accumulated, separate it from the liquid by filtration, 
wash, dry, and ignite it strongly. Exhaust the residue 
thoroughly with hot nitric acid, wash the insoluble part 
in water, dissolve in aqua regia with the aid of a gentle 
heat, adding fresh portions of nitric acid until the j^lat- 
inum is completely dissolved, evaporate the solution on 
the water-bath, with the addition of hydrochloric acid, 
and dissolve the semi.-fluid residue in 10 parts of water. 

24. a. — Plumbic acetate. — Pb (0^1X30 J „. (Acetate 
of lead. PbO, CJI3O3. PbOA.)— The basic acetate, 
Ph {CJI^OX. 2 PhO, is prepared by treating 120 grms. 
of crystallized common acetate (sugar of lead) with 60 
grms. of gently ignited, and then finely pulverized plumbic 
oxide (litharge), and 400 c.c. of water ; let the mixture 
stand some time in a warm place with frequent agitation, 
and finally filter the liquid for use. 

K Plumbic binoxide.— PbO^. 

c. Plumbic oxide. — PbO. Litharge. 

25. a. — Potassic acetate. — KC^HgO^. (Acetate of po- 
tassa. KO,C^H303.) — This should be white and free from 
empyreumatic odor. Dissolve in 5 parts of water. 



§ 25. IlEAGENTS. 19 

h. PotaSSic bisulphate.— KHSO^. (Bisulphate of po- 
tassa. KO,riO,S03.) 

e. PotaSSic chromatc. — K^CrO^. (Chromate of po- 
tassa. KOjCrOg.) — This should give no turbidity with 
argentic nitrate, after acidification with nitric acid. Make 
a cold saturated solution. 

d. PotasSic chlorate. — KCIO^. (Chlorate of potassa. 
K0,C10,.) 

e. Potassic dichromate. — K^Cr„0,. (Bichromate of 
potassa. KO,2Cr0.3.) — This should be recrystallized. 
Dissolve it in 12 parts of water. 

/. Potassic ferricyanide.— K3CygFe. K3Cfdy. (Fer- 
ricyanide of potassium. K^Cy^Fe^.) — This should give 
no blue color with ferric chloride. 

g. Potassic ferrocyanidc— K^Cy^Fe. K^Cfy. (Fer- 
rocyanide of potassium. K.^Cy^Fc.) — Dissolve in 12 parts 
of water. 

A. Potassic hydrate.— KHQ. (Potassa KO,HO.)— 
This should not be changed by amnionic sulphydrate, and 
should efiervesce but slightly if at all with hydrochloric acid; 
the solution obtained with hydrochloric acid in excess, 
when evaporated to dryness should give a residue that is 
at least almost completely dissolved by water ; the same 
solution should give, at the most, but a very slight reac- 
tion for phosphoric acid with amnionic molybdate, and 
should give but a slight flocculent precipitate with am- 
monia in excess, after long standing in a warm place. 
Pure potassa prej^ared from an alchoholic solution of the 
hydrate should give none of these reactions. Dissolve in 
10 parts of water. 

i. Potassic iodide. — KI. (Iodide of potassium.) — This 
is sufiiciently pure as obtained from the druggists. 

h. Potassic permanganate. — K^Mn^Og. (Perman- 
ganate of potassa. KOjMn^O,.) 



20 § 26. REAGENTS. 

/. Potassic SOdic carbonate. — KNaCOg. (Carbonate 
of potassa and soda. KO, NaO, 2 CO^.) — Reciystallize 
some i)otassic sodic tartrate, ignite the salt in a silver 
dish until completely charred, exhaust the black residue 
with water, filter, evaporate the filtrate to dryness in the 
silver dish, and keep the salt in a well stoppered bottle ; 
when it is fused with a little pure sodic nitrate, and the 
residue is dissolved in water and nitric acid, and then am- 
monia added, each in slight excess, no flocculent precipi- 
tate should appear after long standing in a warm place. 

m. Potassic sodic tartrate.— KNaC^H^O^. (Seign- 
ette salt. Tartrate of potassa and soda. KO, NaO, 
CgHjO,^.) — This should be recrystallized once or twice. 
It should give a colorless solution with water. 

71. Potassic Slllphocyaiiate,--KCyS. (Sulphocyanide 
of potassium. KCy S^.) — Dissolve in 20 parts of water. 

2%* Quartz, powdered, — SiO„. — Drench red-hot quartz 
with cold water, and reduce the friable mass to a very 
fine powder. 

27. a.— Soda lime. — Na^CaO,. — This should not effer- 
vesce much with acid, and, when mixed with pure sugar 
and heated to redness, it should evolve no ammonia. 

In order to have the reagent perfectly free from nitro- 
gen, Lawes and Gilbert found it necessary to mix it 
intimately with 1-2 "1^ of sugar or some other non- 
nitrogenous substance, and ignite the mixture in a muffle, 
then to moisten it, and heat it again gently. 

h. Sodic acetate. — NaC2H30„. (Acetate of soda. 
KaO, C^H^Oj.) — This should be colorless and have no 
empyreumatic odor, and should give no reaction with 
ammonic molybdate or baric chloride. Dissolve in 10 
parts of water. 

c. Sodic ammonic phosphate.— NaNHJIPO^ Phos- 
phorus salt, (Pliosphate of soda and ammonia. NaO, 



§ 28. EE AGENTS. 21 

KH^OjHO, PO^.) — This should give a colorless bead when 
fused on platinum wire. 

d. Sodic bisulphite.— HN'aS03. (Bisuljihite of soda. 
KaO,HO,SO,.) — This should give a residue when heated 
with sulphuric acid, whose solution is not changed by 
hydrosulphuric acid or amnionic molybdate. Dissolve in 
10 parts of Avater. 

e. Sodic carbonate. — Na.CO^. (Carbonate of soda. 
NaOjCO^.) — This should be perfectly white, and the solu- 
tion obtained after supersaturation w4tli nitric acid should 
give no precipitate nor color with baric chloride, argentic 
nitrate, or potassic sulphocyanate, nor any reaction with 
ammonic molybdate, nor any insoluble residue of silicic 
acid when evaporated to dryness. Dissolve the crystal- 
lized salt in 3 parts of water, or the anhydrous salt in 5 
parts. Keep some of the ignited salt in the dry form. 

/. Sodic hyposulphite. — Na^SJip . (Hyposulphite 
of soda. NaO,HO,S,0,.) 

g, Hydric di sodic phosphate.— Ka^HPO^. (Phosphate 
of' soda. 2N'aO,HO,PO,.)— This should not be made 
turbid when heated with ammonia, and the precipitate 
produced by argentic nitrate, or baric chloride, should be 
dissolved completely and without effervescence by dilute 
nitric acid. Dissolve in 10 parts of water. 

A. Sodic nitrate. — ]N'aN03. (Nitrate of soda. NaO, 
NO^.) — This should give no reaction with argentic nitrate 
or baric chloride, nor with sodic carbonate. 

28. Starch-paper. — Boil starch with 25 parts of water, 
saturate strips of paper with the liquid, and dry them. 

Tannin.— See acid^ tannic. 

29. Tin. — Sn. — Get the best tinfoil of the druggists, 
or pure tin in small sticks. 

Turmeric-paper. — See curcuma-paper. 

30. Uranic acetate. — (U,0) C,H30,. (Acetate of 



22 § 31. EEAGENTS. 

uranium. (LT^O^jCJIgO^.) — Heat uranic nitrate until a 
small part of the uranic oxide is reduced, digest the 
yellowish-red residue with acetic acid, filter the liquid 
and set the filtrate aside to crystallize ; the crystals are 
composed of uranic acetate, while uranic nitrate remains 
in solution. 

The solution of the acetate should not be changed by 
sulphuretted hydrogen after acidification with hydrochlo- 
ric acid, and should give a precipitate with ammonic car- 
bonate that is entirely soluble in an excess of the reagent. 

31. Urea. — Recrystallize it from its solution in alcohol. 

32. Water, distilled. — H^O.— This can be prepared by 
the analyst himself, if necessary. Dealers in apparatus 
can supply small stills of copper and worms of block-tin, 
put together and ready for use. The water must be 
colorless and tasteless, and it should leave no residue 
when evaporated in a platinum dish. Ammonic sulphide 
should give no color to it, nor should basic plumbic ace- 
tate make it turbid, nor should ammonic oxalate or 
argentic nitrate make it turbid after long standing. 

33. Zinc. — Zn. — This should give no reaction for arsenic 
with Marsh's test, and, when dissolved in nitric acid with 
the aid of heat, it should give no red color with j^otassic 
sulphocyanate. Fresenius recommends that before using 
zinc for reducing ferric to ferrous oxide in the estimation 
of iron by the permanganate process, it should be tested 
by the same process. Dissolve a piece of the zinc in di- 
lute sulphuric acid in the small, long-necked flask, as de- 
scribed in § 52, 5, and, after the flask is filled with water 
and its contents are cold, add a drop of a very dilute so- 
lution of potassic permanganate, and at the same time 
add another drop to the same volume of pure water, and 
stir both mixtures well. The depth of color communica- 
ted to both liquids should be precisely the same. 



§ 34. DETERMINATION OF SPECIFIC GRAVITY. 23 

CHAPTER II. 

ANALYTICAL MANIPULATION. 

Determination of Specific Gravity. 

34. By the specific gravity of a solid or liquid is un- 
derstood its weight as compared with the weight of an 
equal volume of water. 

a. The most obvious method of determining it is to 
weigh equal volumes of the substance and of water. This 
is easily accomplished in the case of liquids, with the aid 
of the so-called specific-gravity bottle or piknometer, an 
instrument made of thin glass and provided with an ac- 
curately ground stopper ; the stopper is sometimes per- 
forated. The weight of the empty bottle is ascertained, 
then its weight when comj^letely filled with water, or 
filled to a mark on the neck, and finally when filled to 
the same extent with the liquid under examination ; be- 
fore weighing, in each case, all adhering particles of liquid 
should be carefully Aviped off with blotting paper ; both 
weighings should be made at as nearly the same tempera- 
ture as possible, or at about 15° C.,the usual temperature 
of the working room. Divide the weight of the liquid 
by that of the water, for the specific gravity of the former. 

h. The specific gravity of liquids is also determined 
with great facility, though with less accuracy, by means 
of the areometer or hydrometer ; this is a glass tube 
closed at both ends, considerably enlarged towards one 
end, and loaded with mercury to make it take a vertical 
position in the liquid, but not with enough to cause it to 
sink under the surface. The use of the areometer depends 
upon the principle, that the less the specific gravity of a 
liquid is, the less its buoj^ant power. The specific gravi- 



24 § 35. AXALYTICAL MANIPULATIOX. 

ties corresponding to the different depths to which the in- 
strument will sink in liquids of different densities, are 
marked on a scale in the upper, slender part of the tube. 
The temperature of the liquid whose specific gravity is to 
be determined with the hydrometer should be as nearly 
15° C. as possible. 

e. As there is a fixed relation between the degree of 
concentration and the specific gravity of a solution of 
any given substance, areometers are constructed, ujDon 
whose scales the amount of the substance in 100 parts of 
its solution is given, instead of the specific gravity of a 
solution of that particular degree of concentration. Thus, 
we have alcoholometers for mixtures of alcohol and water, 
saccharometers for solutions of sugar, acetometers for so- 
lutions of acetic acid, lactometers for milk. 

35. a. — To determine the specific gravity of a solid, we 
may weigh it first in the air, and then while immersed in 
water, and suspended from the arm of the balance by a 
fine thread or hair. The difference between these two 
weights, divided into the weight of the body in the air, 
will give its specific gravity. 

b. Or, if the substance is in the form of a powder that 
is insoluble in water, we may weigh it first by itself in 
the specific-gravity bottle, then fill the bottle with water, 
as in § 34, «, and weigh again. The difference between 
the weights of water that the bottle will hold, with and 
without the substance in it, which is the weight of a vol- 
ume of water equal to that of the solid substance, divided 
into the weight of the substance itself, will give its sjdc- 
cific gravity. 

c. Or, taking advantage of the fact that a cubic centi- 
metre of water weighs very nearly one gramme at com- 
mon temperatures, we may make a rough determination 
of the specific gravity by filling a 500 c.c. graduated cyl- 
inder exactly up to the 250 c.c. mark, then j)utting a 



§ 36. SOLUTION. 25 

^\-ciglied quantity of the substance (100 or 200 grms.) in 
tlie cylinder, shaking the mixture well so as to disengage 
huhbles of air, and observing the volume occupied by 
butli the substance and the water ; the increased volume, 
which represents that of the substance added, expressed 
in cubic centimetres, divided into the weight of the sub- 
stance taken, expressed in grammes, Avill nearly equal the 
specific gravity. 

d. If the substance is soluble in water, some other liquid, 
like alcohol or naptha, must be used. Determine the 
specific gravity of the substance with reference to this 
li(|uid, by the same rules as above, and then multiply the 
result by the specific gravity of the liquid used, with ref- 
erence to the common standard, water ; the product will 
be the specific gravity of the substance with reference to 
the same standard. 

e. The specific gravity of a substance may be deter- 
mined roughly, but very expeditiously, as, for example, 
of 2:»otatoes, by putting several samples in a shallow dish 
containing a saturated solution of common salt, and add- 
ing water with constant stirring, until the buoyant power 
of the liquid is diminished to such a degree that half the 
samples swim at the surface, and half sink to the bottom ; 
it can then be assumed, with sufficient accuracy for some 
purposes, that the average specific gravity of the article 
under examination is the same as that of the solution, 
and this can be determined Avith the aid of the hydrome- 
ter (§ 34, h). 

SOLUTION. 

36. In order that a substance may be analyzed accord- 
hig to the methods described in the following pages, it 
must be brought into solution if not already dissolved. 
The solvents most commonly used are water, hydrochloric 
acid, and nitric acid, for inorganic substances, and water, 
2 



26 § 36. ANALYTICAL MAXIPULATIOX. 

alcohol, and ether, for organic matters. As the manner of 
making the solution is described in each case, when spe- 
cial directions are necessary, but little need be said on the 
subject here. As a general rule, heat increases the sol- 
vent power of the dissolving agents to a considerable ex- 
tent, and hence it should always be applied, unless the 
solution is very easily accomj^lished without, or unless di- 
rections are given to the contrary. Time is often an im- 
portant element in effecting solution, and hence long con- 
tinued digestion at a moderately high temperature may 
be useful, or even necessary. A great excess of strong 
acid in a solution to be analyzed often causes much 
trouble ; hence, as little acid as j^ossible should be used, 
and in case a large quantity has been added to the sub- 
stance, it should, in most cases, be removed subsequently 
by evaporation almost to dryness. 

Unless a substance is readily and completely soluble, it 
is essential that it should be as finely divided as possible, 
and, to this end, it should be ground to a fine powder in 
a porcelain mortar, or, better still, an agate one. 

In order to reduce a substance to a sufficiently fine 
powder, it is sometimes necessary to levigate it, which 
means simply to grind it in the agate mortar with the 
addition of water enough to make a thin paste, until no 
grittiness can be felt under the pestle, nor any grating 
sound heard. Then rinse the contents of the mortar 
into an evaporating dish, dry the substance thoroughly 
over the water-bath, and mix the dry residue together 
carefully by further grinding in the mortar. 

In making a solution for quantitative jDurposes, when 
the loss of even a minute part of the substance would 
impair the accuracy of the results obtained, if the mixture 
of substance and solvent is to be boiled, or if the sub- 
stance is a carbonate, and is to be treated with an acid, it 
is best to operate in a flask placed on its side, or with its 
mouth loosely stoppered by a small funnel, or in a beaker 



§ 37. EVAPORxiTIOX. 27 

covered with one of tlic large watch-glasses now so much 
used for this purpose. The flask with the funnel in its 
mouth is better for the solution of carbonates, since fresh 
quantities of acid can be conveniently added from time to 
time. When the solution is finislied, carefully rinse the 
funnel or watch-glass into the flask or beaker. 

Heat is most conveniently applied to a mixture of sub- 
stance and solvent with the aid of the water-bath, or sand- 
bath, in making solutions for quantitative purposes, and 
often in qualitative analysis also. When it is necessary 
to boil the mixture of substance and solvent for a consid- 
erable time, and the solvent is more or less volatile, it 
is best to connect the flask with the loicer end of a Lieb- 
ig's condenser ; the vapor of the liquid as it is condensed 
flows back into the flask, and it is unnecessary to renew 
the solvent until it is quite saturated. See § 39, c. 

EVAPORATION. 

ST. A liquid may be evaporated either to get rid of a 
superabundance of water, that makes the solution too di- 
lute, or to expel an excess of acid, or for the jDurpose of 
weighing what it has in solution. In the first and second 
cases, the operation may be performed in porcelain dishes, 
miless the solution is strongly alkaline. 

a. In the third case, if the quantity of the liquid is 
large, it may be evaporated to a small bulk in a porcelain 
dish, and then carefully transferred to a platinum dish or 
crucible. Or the original solution may be put into the 
platinum dish in small quantities at a time ; if, however, 
the solution contains free chlorine, or nitric and hydro- 
chloric acids together, it must be evaporated in a porcelain 
dish until no more fumes of chlorine are evolved ; the 
residue may then be transferred to the platinum vessel, 
and the evaporation continued. 

When a considerable quantity of a liquid is to be evap- 



28 § 37. ANALYTICAL MANIPULATION. 

orated, the operation may be j^erformed at first directly- 
over tiie lamp ; Lut in quantitative work the evaporation 
should be completed on the water-bath in all cases ; if the 
original quantity of the solution is small, it is better to 
conduct the wliole evaporation on the water-bath. 

If the evaporation is connected with quantitative work, 
the dish should never be more than three-fourths filled, 
and the solution should not be allowed to boil at any time 
in an open vessel ; evaporation will, however, proceed 
quite rapidly in a flask placed partly on its side, and in 
this case a:entle boilino- may be allowed. 

Unless the evaporation is performed in a room set ajoart 
for the work, and eyitlrely free from dust, solutions should 
be kept covered with filter-paper during the operation ; 
the paper should be supported by glass rods, or a glass 
triangle, laid over the dish in such a manner that it cannot 
como in contact with the liquid ; if the solution is strong- 
ly acid, the paper should have been well washed with 
acid, as directed for Avashing filters § 39, a / otherwise, 
drops of acid, that have condensed on the glass rods 
and come in contact with the paper, may fall back into 
the liquid and carry with them inorganic substances that 
were dissolved out of the paper. 

To j)revent the salts in solution from being deposited 
on the sides of the dish above the liquid, and even over 
the edge, smear the rim of the dish, just below the edge 
on the inside, with the thinnest possible coat of tallow. 
Or, fit the dish in a little jacket of fire-clay, in such a 
manner that the part of it above the liquid shall be kept 
very hot. Or, turn the crucible on its side, and apply 
the flame of the lamp just above the surface of the liquid. 

h. When, as is often the case in agricultural analysis, 
potassa or soda is to be estimated in a solution containing 
a large quantity of ammoniacal salts, and from which 
these salts are to be removed by evaporation to dryness 
and ignition, Fresenius recommends to evaporate the so- 



§ 38. PRECIPITATION. 29 

liition to dryness in a porcelain dish on the water-bath, 
dry the residue thoroughly at a temperature a little above 
100° C, transfer it to another dish with the aid of a 
spatula, rinse the porcelain dish with a little water into 
the crucible in which the residue is to be finally ignited, 
evaporate these Avashings to dryness, then ignite the dry 
residue, obtained above, in small portions at a time, and 
finally rinse the dish that contained it into the crucible, 
with the aid of a little finely joowdered amnionic chloride, 
and ignite again. The dish with the residue should be 
kept in the desiccator while waiting for the ignition. 

PRECIPITATION. 

38. Precipitation is usually resorted to in order to sep- 
arate certain substances from others in the same solution, 
or simply from the solution itself; it consists in adding 
some reagent to the solution, which causes the substance 
or substances in question to enter into an insoluble form. 
The operation is usually performed in beakers, because, 
from these, the precipitate is more easily transferred to 
the filter. 

Care must be taken not to use too large an excess of 
the precipitant, and yet there must be no doubt at all that 
enough has been added ; if the precipitate does not settle 
speedily, so that the effect of the addition of a fcAV more 
drops of the reagent can be observed, a small i)ortion of 
the mixture should be thrown on the same filter that is 
finally to receive the wdiole of the precipitate, and the 
necessary test can be applied to the filtrate ; this small 
portion that has been separated from the main part of the 
liquid should then be mixed with it again, before more of 
the precipitant is added. 

The solution and the reagent should always be well 
mixed by stirring, and, in most cases, the solution should 
be so dilute that, when the precipitate settles, it will not 



80 § 38. ANALYTICAL M ANIPULATl OlS". 

occupy more than one-third or one-fourth the space taken 
up by the liquid above it ; and, moreover, for convenience 
in filtration, the beaker should not be more than two- 
thirds or three-fourths filled by the mixture. 

A few precipitates may be filtered out at once, in quan- 
titative analysis, but in most cases digestion in a warm 
place for a longer or shorter time, is required. The beak- 
er should be carefully covered during the digestion, so 
that no particle of dust can get in, and the operation is 
most conveniently performed on the sand-bath. 

AYhen about to transfer the contents of the beaker to 
the filter, smear a very little tallow under the lip of the 
former, wet a glass rod in the liquid, and hold this wet 
rod against the lip of the beaker in such a manner that 
the liquid will run down the rod and against one side of 
the filter. 

Of course every particle of the preci^^itate must be 
transferred to the filter if the two are to be weighed 
together, with or Avithout ignition. Most of the preci- 
pitate can be rinsed out of the beaker by means of 
the jet from the washing-bottle; if any particles re- 
main adhering to the glass, they may be loosened w^ith 
a stiff feather ; or, when the precipitate is to be ignited 
before being weighed, a quarter or a half of a filter, of 
the same size and kind as that in the funnel, may 
be moistened slightly and rubbed over the sides and bot- 
tom of the beaker with the aid of the glass rod, or of 
glass-poiiited phicettes, and then transferred to the filter, 
with most of the remainder of the precipitate adhering 
to it ; a little subsequent rinsing with the wash-bottle 
Avill leave the beaker thoroughly cleansed ; or the precipi- 
tate that adheres obstinately to the sides of the beaker 
may be dissolved in very dilute acid, and re-precipitated 
on neutralization of the acid with ammonia or soda, and 
the addition of a little more of tlie precipitant. If the 
second method of cleaning the beaker is followed, remem- 



I 



§ 39. FILTRATION. 31 

ber to subtract the weight of l'|, or 1' |., filter-ash from 
the weight of the ignited residue instead of 1 as usual. 

FILTRATION. 

39. a. — Solid i:)articles arc separated from the liquids 
with which they may be mixed by the process of filtra- 
tion, referred to in the preceding paragraph, which con- 
sists simply in passing the liquid through porous unsized 
paper, that intercepts the solid. 

Paper, already cut in convenient sizes, can be had of 
apparatus dealers. For quantitative purposes, filters of 
Swedish paper should be used, or common white filters 
that have been washed in dilute acid ; to wash filters, 
pour over them, in layers of moderate thickness in a large 
evaporating dish, a mixture of one part of hydrochloric 
acid and nine parts of water; digest for several hours at 
a moderate temperature, wash v>dth distilled Avater by de- 
cantation until the washings no longer redden litmus, 
transfer the bunches of j)aper to blotting paper, and leave 
them undisturbed until the filters can be separated from 
each other without being torn. These washed filters 
are more suitable for filtration by Bunsen's process than 
those of Swedish paper, as they are stronger and less lia- 
ble to be torn. 

To make the filter, fold the circular piece of paper twice 
m directions at right angles to each other, and through 
the centre ; open the quadrant thus formed in such a man- 
ner as to make a conical cavity, put it in a glass funnel, 
which should be at least 3-5 millimetres larger than the 
filter, wet the latter with a little water from the washing- 
bottle, and press it closely against the glass throughout 
with the finger. 

The filter should never be filled with the liquid to 
within less than 6 mm. of the top, and should not ordi- 
narily be much more than half filled with the precipitate 
when the liquid has drained ofi*. 



I 



32 S 39. ANALYTICAL MANIPULATION. 



Most liquids may be filtered much more rapidly Avben 
hot, and many precipitates are much less liable to pass 
through the filter, or to choke it up, when formed in nearly 
boiling hot solutions by hot reagents. 

When possible, it is best to let the solid matter settle 
to the bottom of the vessel containing the mixture of 
liquid and precipitate, then to decant as much as possible 
of the clear, supernatant liquid on the filter, pour fresh 
distilled water over the contents of the beaker, stir w^ell, 
and perhaps heat almost to boiling, let the precipitate set- 
tle, and decant the liquid again ; this may be repeated a 
number of times before putting the solid substance on the 
filter. 

If the precipitate is to be dissolved without weighing 
or ignition, it is generally best to wash it altogether by 
decantation, and then to pour the solvent over the filter 
through which the decanted liquid was passed, and collect 
it in the beaker containing the main portion of the washed 
precipitate ; the precipitate may then be iligested with 
the reagent if necessary, and, afterwards^ the filter well 
washed out with water, that is added to the solution just 
made ; in this way Ave may avoid any considerable dilu- 
tion of the solvent before it has had time to act on the 
substance to be dissolved. If the solvent is one that, in 
its concentrated state, Avould attack the paper, it may be 
poured at once over the precipitate in the beaker, while 
another portion may be diluted somewhat, and passed re- 
peatedly through the filter, to take up the small quantity 
of the substance on thrit. 

The thorough washing of precipitates and residues, 
that is so essential in quantitative analysis, and is often 
not unimportant in qualitative work, may sometimes be 
greatly facilitated by this process of decantation, particu- 
larly if the solid is one that settles readily ; but if Bun- 
sen's process of filtration is followed, decantation may be 
dispensed with. 



§ 39. FILTKATIOX; BUNSEN's PROCESS, 33 

In washing precijjitatcs on the filter, the Avashing-bottle 
is an indispensable aid. This consists simply of a flask 
of a capacity of 150-1000 c.c, according to the purpose 
for which it is to be used, closed by a good cork that is 
pierced with two holes ; through one of these holes passes 
a glass tube, 8 or 10 cm. long, that extends just beyond 
the coi'k on tlie inside, and, outside, is bent at an angle 
of about 110°; the tube that passes through the other 
hole extends nearly to the bottom of tlie flask, and, out- 
side, is bent at an angle of about 70°, and drawn out to a 
small jet at the end; water in the flask is forced out at 
this jet on blowing air in at the mouth of the shorter 
tube. 

Each portion of water with which a precipitate on the 
filter is washed should be allowed to pass through com- 
pletely before another is added, and the precij^itate should 
be stirred up as much as possible by the jet from the 
wash-bottle with each fresh addition. 

Insoluble residues and precipitates must be washed, 
particularly in quantitative operations, as long as the wash- 
water carries off any notable quantity of matters in solu- 
tion ; the washings are tested by evaporating a drop to 
dryness on platinum foil, to see if any residue is left, or 
by a chemical test, as, for example, when washing a pre- 
cipitate of baric sulphate that was formed by adding 
baric chloride to a solution of a sulphate ; as long as any 
cf the soluble chloride remains in the pores of the filter, 
or adheres to the precipitate, and is taken up by the 
vv'ater, the washings will give the usual reaction for 
chlorine with argentic nitrate (§ 63). 

When the contents of the filter are to be weighed or 
ignited, dry the whole together in the drying-chamber or 
air-bath, with the funnel well covered with filter paper. 

h. A method lately devised by Bunsen {Annalen der 
Chemie, 148, 270. American Journal of Science and 
Art, 2d Series, 47, 321) for increasing the rapidity of fil- 



34 § 39. ANALYTICAL MA^IPULATION. 

tration, and of the Avashing of precipitates, promises to be 
very useful. 

He supports tbe filter by a hollow cone of thin plat- 
inum foil in the throat of the funnel, and then rarefies 
the air in the funnel-tube ; the excess of pressure on the 
liquid in the filter causes it to flow through very rapidly, 
while there is no danger of tearing the paper. 

To make the platinum funnel, a cast of the glass funnel 
must first be taken. Select a funnel with perfectly smooth 
and straight sides, and opening at an angle of 60°, fit in 
it a piece of oiled writing paper in such a manner that it 
shall touch the glass everywhere, like an ordinary well- 
fitted filter, and fasten the paper in place with two or 
three drops of sealing-wax around the rim. Half fill the fun- 
nel then with gypsum paste, into which, before it hardens, 
a plug of wood is inserted, to serve as a handle. When the 
gypsum cone has hardened, remove it from the funnel, oil 
the paper again, and plunge it, with the paper still adher- 
ing, into a large porcelain crucible filled with another por- 
tion of gypsum paste ; when this mould has hardened, 
take the cone out and rub off the paper with the fingers. 
g !N"ow, cut out a piece of thin plat- 

inum foil weighing about 0.154 grm., 
of the precise shape and size repre- 
sented in the adjoining figure, with a 
slit running from 1) to «, the centre 
of the circle of which the arc, c e d^ 
forms a j^art ; ignite it in the flame of 
the lamp to make it perfectly flex- 
ible, lay the gypsum cone on it so that the apex 
of the cone shall coincide with a^ bring up the edge, a h J, 
and press it well against the cone, and then do the same 
with the edge, ab c ; after fitting the foil to the cone as 
perfectly as possible Avith the fingers, put the whole in the 
mould in the crucible, and revolve the cone back and 
forth vmtil the platinum has taken the exact shape of the 




§ 39. filtration; buxsex's process. 35 

plaster casts, and retains its form when removed from the 
mould ; if found necessary, it may he ignited once more 
and shaped in the mould with the cone. It may be sol- 
dered at its uj^per edge by a grain of gold and borax, so 
that it Avill be less liable to get out of shape, but this is 
not necessary. If properly made, the light should not be 
visible through tlie point of this platinum funnel when it 
is held before the Avindow. 

"With the platinum funnel in tlie throat of the glass- 
funnel, adjust the paper filter, which may be much small- 
er than would be used in the ordinary way of filtering, in 
the usual manner, with special care to secure perfect con- 
tact between the filter and the funnel at all points. Con- 
nect the tube of the funnel with a large, strong glass 
flask, by means of a rubber cork jiierced with two holes, 
so that the tube extends about G cm. beyond the cork ; 
through the other hole pass a short glass tube so that it 
extends just to the lower surface of the cork ; this tube 
should be bent once at a right angle outside of the flask ; 
it may be connected with a small brass stop-cock by 
means of a short rubber tube with a small bore and very 
thick walls ; all the rubber tubing used in the apparatus 
should be of this kind. 

Xow, pour the liquid to be filtered on the filter, rarefy 
the air in the flask, and keep the former full as long as 
any of the liquid remains. The precipitate may be al- 
lowed to come within 1 mm. of the edge of the filter. 

In washing the precipitate, pour the water from a flask, 
fill up to about a centimetre above the rim of the filter, 
with care not to disturb the precipitate, and let each por- 
tion of water drain ofl" completely before adding a fresh 
quantity ; thus the washing may be thoroughly efi'ected 
in a wonderfully short time ; if the vacuum in the flask 
is nearly perfect, or the pressure on the filter is nearly an 
atmosphere, three or four washings suflice, even in the 
case of precipitates that arc the most diflicult to wash. 



36 § 39. ANALYTICAL MANIPULATION. 

Moreover, the precipitate is so completely deprived of its 
water, that it may be easily removed from the filter, or 
can be ignited at once without further drying. 

To ignite the precipitate at once, Bunsen directs to wrap 
the filter around it, put the whole in the crucible, set the 
latter on its side as usual, apply the heat at the top of 
the crucible first, and gradually carry it towards the bot- 
tom as the filter is burned. 

The rarefaction of the air may be produced in various 
ways. The flask may be connected with the upper end 
of a water-pipe 30 feet high in such a manner as to make 
a Sprengel's air-pump. Desaga, of Heidelberg, furnish- 
es a complete apparatus for this purpose. 

Or, an air-tight connection may be made between two 
large glass bottles, or demijohns, by means of a long piece 
of thick walled rubber tubing ; then put one bottle filled 
with water on a high shelf, while the other is put on the 
floor, connect the filtering-flask with a tube leading just 
through the cork of the upper bottle, allow the water to 
flow from the upj^er bottle to the lower one, while pro- 
vision is made for the escape of the air from this lower 
bottle ; the rarefaction of the air in the filtering-flask will 
follow. When all the water has flowed from the upper 
to the lower bottle, their relative positions may be re- 
versed, the proper connection made between the filtering- 
flask and the upper bottle, and the filtration continued. 

Or, a small demijohn may be closed by a rubber cork 
through Avhich passes a glass tube, connected with a 
small brass stop-cock; connect the demijohn w^ith an air- 
pump, exhaust the air, close the stop-cock, connect the 
demijohn with the filtering-flask, and open the stop-cock 
when all is ready for the filtration. In order to j^revent 
acid fumes or ammonia coming from the filtered liquid 
from injuring the stop-cock, a Avash-bottle, containing 
sodic hydrate or sulphuric acicl, may be interposed. (J. 
M. Crafts.) 






§ so. FILTRATIOX. 37 

For fuller details in regard to this mode of filtration 
we refer to tlie original articles. 

c. When several portions of a solvent, such as water, 
alcohol, or ether, are to be made to act on a substance, 
each portion can be readily separated from the substance 
by the foUoAving contrivance. 

Close the flask with a rubber cork pierced with two 
holes ; through one of these pass a short bent tube, like 
the shorter tube of the common washing-bottle, and in 
the other hole fit a tube which is widened out, funnel-like, 
at one end, but not so much as to prevent its being put 
into the flask easily ; near the other end, this tube is bent 
at an acute angle, and the end is drawn out to a point 
and left with a pretty large opening, after the fashion of 
the other tube of the washing-bottle ; the long arm of 
the tube should reach nearly to tbe bottom of the flask, 
and have a piece of fine linenfirmly bound over its mouth. 

The substance and the solvent having been digested in 
the flask, when the solvent is supposed to be saturated, 
and it is desired to re2:)lace it by a fresh quantity, force 
air into the flask by the shorter tube and the solution will 
be expelled, and at least partially filtered on its way 
through the muslin ; then, if the end of the longer tube 
is immersed in a fresh quantity of the solvent, this may 
be drawn into the flask by suction at the mouth of the 
short tube. 

If heat is used, the mouth of the short tube may be 
connected with the lower end of a Liebig's condenser ; 
then the vapors of the solvent are condensed, and the 
liquid flows back into the flask, and the ebullition can be 
maintained as long as is desired without the necessity of 
adding fresh quantities of the solvent to replace what is 
lost by evaporation ; when it does become necessary to 
replace this portion of the solvent by a fresh one, the rub- 
ber tube that connects the flask with the condenser may 
be closed with a clamp, and, the application of heat being 



38 § 40. ANALYTICAL MANIPULATION-. 

continued, tbe liquid will be forced out through the mus- 
lin filter; on immersing the open end of the longer tube 
in a fresh quantity of the solvent, and removing the lamp, 
this liqui<:l will floAV in. 

The solution may not be perfectly clarified in passing 
through the linen filter, in which case it will have to be 
filtered again through paper. 

To efiect more perfect filtration, a thick mat of gun- 
cotton may be bound over the linen ; this layer of cotton 
should not be anywhere less than 14 mm. thick. 

WEIGHING OF RESIDUES AND PRECIPITATES. 

40. When it is possible, residues or precipitates are ig- 
nited before being weighed. 

This ignition may be performed in two ways. 

a. If the substance is not altered in its chemical com- 
position l)y contact with burning organic matter, or at 
the somewhat high temperature that is sometimes neces- 
sary to effect the complete incineration of the filter, roll 
the well-dried filter together around the precipitate, put 
the whole in the previously ignited and weighed crucible, 
cover and heat, at first very gently ; when the filter is 
completely charred and no more smoke is given ofi*, turn 
the crucible on its side, lay the cover jiartly on the edge 
of the crucible and partly on the triangle, and heat the 
contents of tbe crucible until the ash is quite white. 

5. If the filter may not be burned in direct contact 
witli the precipitate, crush and work it gently between 
tbe fingers over a sheet of glazed j^aper, to loosen tbe pre- 
cipitate as much as possible, place the crucible on the 
glazed paper, and empty the contents of the filter into it. 
Put tbe crucible on the porcelain plate belonging to the 
Bunsen's burner, open the filter on another j^iece of 
glazed paper, fold its edges up so as to make a little tray, 
with a soft feather carefully brush into tbis tray any 



§ 40. WEIGIIIXG OF RESIDUES AND PRECIPITATES. 39 

particles of the precipitate that may have fallen on tlie 
first piece of paper, roll the filter up, enclose it in a short 
spiral on one end of a platinum wire that was weighed 
with the crucible, hold it over the crucible, and set fire to 
it ; by ajiplying the charred filter to the flame of the 
lamp two or three times it may be almost completely hi- 
cinerated ; finally, either let the ash and the wire drop 
into the crucible and ignite the whole four or five minutes, 
or until the ash is white, or, in case the filter-ash must be 
kept entirely separate from the precipitate, let the two 
drop into the hollow lid of the crucible, and ignite the 
precipitate and ash separately. 

The glazed paper used above should be of a light color 
if the ^precipitate is dark-colored, and vice versa, and the 
whole operation should be performed in a place free from 
currents of air. 

c. If the quantity of the precipitate is very small, and 
yet is of such a nature as to be partly reduced to a lower 
degree of oxidation if ignited with the filter, the ignition 
may be performed as in a / when it is completed, put a 
piece of dry amnionic nitrate in the crucible, cover well, 
and ignite again, but very gently at first. 

Ferric oxide or baric sulphate may be ignited in this 
way when nothing better can be done. 

Sometimes, when a portion of the filter is very difficult 
to incinerate completely, the combustion may be facilita- 
ted by adding a little amnionic nitrate as above. 

After weighing, subtract the weight of the filter-ash, 
which has been determined once for all for the particular 
kind and lot of 2>iiper and size of filter used, by the incin- 
eration of half a dozen or a dozen together, and dividing 
the total weight of the ash thus obtained by the number 
of filters burned. 

d. If the substance to be weighed cannot be ignited, a 
filter should be previously thoroughly dried in the steam 
or air-bath at the same temperature to which it is after- 



40 § 41. ANALYTICAL MANIPULATION. 

wards to be exposed witli the precipitate, and weighed, 
either between two watch-glasses with ground edges and 
fitting well together, or in a stoppered glass tube ; after 
careful drying Vv^ith the precipitate, it is again weighed in 
the same manner. It should then be dried an hour 
longer and weighed again, and this should be repeated 
until a constant weight is obtained. Swedish filter-paper 
or washed filters should always be used in this operation. 

e. The substance that has been dried or ignited, and is 
to be weighed, should always be allowed to cool undef a 
bell-glass over concentrated sulphuric acid, or in the des- 
iccator more commonly used for this purpose ; this desic- 
cator consists simply of a short and wide glass cylinder, 
with a ground edge upon which a ground glass -plate will 
fit closely, particularly if the edge is smeared with a little 
tallow. 

The pair of watch-glasses containing the dried filter, 
or the crucible Avith the ignited precipitate, rests on a tri- 
angle in the cylinder over . fused calcic chloride, with 
which the bottom is covered. 

No object should be weighed until it is entirely cold. 

y. Platinum vessels, after having been heated by gas, 
should be rubbed with a little sand on the moistened fin- 
ger. The sand should be fine, and all its grains should 
be rounded. The crucible should also be cleaned from 
time to time by fusing a little potassic bisulphate in it. 
The crucible should be supported over the lamp on stout 
platinum wire, which is stretched from side to side of a 
larger iron-wire triangle, in such a manner as to make a 
second triangle inside of, and about 6 mm. smaller than, 
the iron triangle. 

MEASURING AND DIVIDING SOLUTIONS. 

41. For these purposes graduated pi2:)ettos and cylin- 
ders, and ^1^, ^ |„, and 1 litre flasks are used. 



§ 41. MEASURING AND DIVIDING SOLUTIONS. 41 

The analyst should test the correctness of the gradua- 
tion of his instruments before using them, by comparing 
them with each other; the ^\^ litre flask should require 
just as much water to fill it twice up to the mark on the 
neck as is required to fill the ^ |., litre flask once up to the 
mark on its neck. In the same way the ' |, litre flask 
should be compared with the 1 litre flask, and these with 
the graduated cylinders, and the pipettes Avith each other 
and the graduated cylinders. 

When a certain quantity of any standard or titrated 
solution is to be measured out with a pipette or flask, the 
instrument should either bo dry on the inside, or it should 
be rinsed out with a little of the solution to be measured, 
and the last drop of the solution that remains in the point 
of the pipette should either always be allowed to remain 
there, or it should always be blown out into the vessel 
containing the measured solution ; the same course should 
be followed in testing the graduation of the pipettes. 

To read ofl" the height of a solution in a burette or 
other graduated instrument, be sure, first, that it is in a 
vertical position, so that the surface of the liquid in it 
will be horizontal ; then place the cylinder between the 
eye and a brightly illuminated white wall, and read the 
height of the lower surface of the dark zone that is read- 
ily seen under these circumstances just beneath the sur- 
face, while the eye is in the same horizontal plane. 

In filling a Mohr\s burette, fill up to above the zero 
mark with the solution, and quickly open wide the clamp 
for a moment so that the rubber tube and the glass tube 
beloAV the clamp Avill be completely filled ; then open the 
clamp a little and allow the liquid to flow out, drop by 
drop, until the dark zone, mentioned above, reaches the 
zero mark. 

The temperature of all measured liquids should be as 
nearly 15° C. as possible. 

When the quantity of a solution to be divided is not 



42 § 42. ANALYTICAL MANIPULATION. 

too large, the division may be more accurately made by 
weighing than by measuring. Get the Aveight first of the 
whole amount of the liquid, in a small flask, pour out 
about the quantity desired for a particular analysis, and 
weigh the flask again with the remainder of the liquid ; 
pour out another quantity and Aveigh again, and so on 
until the division is completed. 

For this purpose, a flask with a little spout, attached, 
just below where the neck widens out into the body, will 
be found very convenient. 

CALCULATION OF RESULTS. 

42» The results of an analysis are usually calculated so 
as to give the j^cr cent composition of the compound 
analyzed. 

If the substance determined is weighed or estimated in 
the form in which it existed in the compound, and it was 
determined in the undivided solution of the same, noth- 
ing remains to be- done but to estimate the percentage by 
a simple rule-of-three calculation, in which the amount 
taken for analysis is the first term, the amount of the sub- 
stance found the second, and 100 the third. 

If the substance v/as determined in a fractional part of 
the solution, the same fractional j^art of the weight of the 
compound taken for analysis must be made the first term 
of the proportion ; or the amount of the substance found 
may be estimated for the v\^holc amount of the original 
solution by multiplication by the proper number, and this 
product is then made the second term of the proportion, 
the first term being the v/eight of the vfhole amount taken 
for analysis. 

In gravimetrical analysis the substance is usually 
weighed in the form of some insoluble compound that 
did not exist at all in the compound analyzed, and the 
amount of the substance in the weight that was found of 
this insoluble compound must first be calculated. 



§ 42. CALCULATION^' OF RESULTS. 43 

Tliis may bo effected by a rule-of-three calculation also, 
in Avhich the molecvilar weight of the insoluble sub- 
stance is made the first term, the vf eight of the substance 
sought in a molecule of the nisoluble substance the second, 
and the Aveight of the insoluble compound found the third. 

For example, in a determination of sulphuric acid, SO3, 
l.lo grm. of baric sulphate was found; then we have 

BaSO, : SO3 = BaSO, : SO^ 

233 : 80 = 1.13 : 0.3879 grm. 

The same result can be more expeditiously obtained, 
however, with the aid of Table III, where for each special 
case a part of this calculation has already been perform- 
ed, namely, the division of the second term by the first ; 
nothing is left to be done, therefore, but to multiply the 
weight of tlic insoluble compound found, whose name is 
given in the first column, by the decimal in the second 
column against the name of the substance sought in the 
third column. In the above-mentioned case we find, on 
consulting the table, the j^roper decimal against the 
names sulphuric acid and baric sulphate is 0.3433, A\hich 
multiplied into 1.13 grm. = 0.3S79. 



44 8 43. BASES AND ACIDS WITH KEAGENTS. 



CHAPTER III. 

BEHAVIOR OF THE MORE COMMON BASES AND ACIDS WITH 
REAGENTS, AND THEIR QUANTITATIVE ESTIMATION. 

43. The substances for whose qualitative detection or 
quantitative estimation directions are given in the follow- 
ing pages, are as follows. 

1. Inorganic^ basic elements. — Potassium, sodium, bari- 
um, calcium, magnesium, aluminium, iron, manganese, zinc, 
lead, and copper. 

2. Volatile, basic radical. — Ammonium. 

3. Acid elements and inorganic acids. — Arsenic, chlo- 
rine, iodine, fluorine, sulphur, and sulphuric, phosj^boric, 
carbonic, silicic, and nitric acids. 

4. Compound^ acid radlccds. — Cyanogen and ferrocy- 
anogen. 

5. Organic ccrids. — Oxalic, acetic, tartaric, citric, malic, 
uric, hippuric, lactic, and tannic acids. 

G. Indifferent organic substances. — Cellulose, starch, 
sugar, gum, albuminoids, urea, flit, and alcohol. 

POTASSIUM. K. 39.1 

44. — Salts of potassium, with all the acids mentioned 
in § 43, except tartaric, are easily soluble in water. The 
tartrate is soluble in free alkali or mineral acid, or in 
considerable water. 

Reactions. — 'In tolerably concentrated, neutral or 
slightly acid solutions of potassic salts, containing hydro- 
chloric acid or a soluble chloride, platinic chloride, PtCl^, 
gives a yellow, granular, crystalline precipitate, K.^PtCl^, 
which is sparingly soluble in water, and nearly insoluble 
in alcohol. Its solubility is slightly increased by the 



§ 44. POTASSIUM. 45 

presence of free liydrocliloric acid. No precipitate will 
be given by the reagent in a very dilute solution of the 
potassic salt, but if such a solution is evaporated nearly 
to dryness with a little platinic chloride, and alcohol is 
added to the residue, the yellow double salt remains nn- 
dissolved. 

If a drop of a solution of a potassic salt is evaporated 
to drjmess in the platinum- wire loop, and tlie loop with 
the residue on it is held at the end of the inner blowpipe 
flame, or in the corresponding part of the flame of the 
Bunsen gas-burner, a violet color is communicated to the 
flame beyond the wire. Viewed through thick blue glass, 
this color has a more reddish ap^^earance, but the light is 
not entirely absorbed ; the presence of sodium, barium, 
calcium, and copper, may interfere with this reaction. 

In a silicate, tliis reaction for j^otassium may be ob- 
tained by fusing it, in a fine powxler, with pure gypsum, 
treating the fused mass wdth water, filtering, and testing 
the filtrate. 

Quantitative estimation, — Potassium may be deter- 
mined as potassic chloride, KCl, potassic sulphate, K^SO^, 
or potassic platinic chloride, K.PtClg. 

The first two salts are soluble in w^ater, and therefore 
cannot be obtained by precipitation ; other metals and 
acids being removed from the solution by methods here- 
inafter described, the pure salt is then left as a residue on 
evaporation to dryness. 

a. Determination as potaSSic chloride. — The solution 
being freed from other metals and acids, evaj^orate it to 
dryness over the w^ater-bath, and ignite the residue in a 
well covered platinum crucible, very gently for a consid- 
erable time at first, to avoid the decrepitation and conse- 
quent loss that might result from too rapid heating; 
finally, heat the crucible to a dull red for a short time. 
The residue contains 52.41° 1^ of potassium. 



46 § 44. BASES AND ACIDS WITH KEAGENTS. 

h. Determination as potassic Sulphate. — The solution 
beinof freed from other metals and from non-volatile acids, 
as directed in each special case, evaporate it to dryness 
and ignite the residue in a platinum crucible, aB directed 
for the ignition of potassic chloride, except that it may 
be more strongly heated at the close of the operation. 

If volatile acids, such as hydrochloric, nitric, or acetic, 
are present in the solution containing the potassium to be 
determined, sufficient sulphuric acid must be added before 
evaporation to expel them ; in order, however, to avoid 
the disagreeable operation of expelling a large excess of 
sulphuric acid also, it is well to add but littLe at first ; the 
evidence that enough has been used will be found in the 
evolution of abundant white acid fumes towards the close 
of the evaporation ; if these fumes do not appear, of 
course a little more acid must be added, and the evapora- 
tion continued. 

After igniting the residue in the platinum crucible 
gently for a little while, put in a small fragment of well 
dried amnionic carbonate, and ignite again while the 
crucible is loosely covered, very gently at first, and then 
gradually raise tlie heat to a full red ; repeat this addition 
of amnionic carbonate and the subsequent ignition as 
long as there is any change in weight. 

The ignition with amnionic carbonate facilitates the ex- 
pulsion of the second equivalent of sulphuric acid from 
the potassic bisulphate, and it should be used in the man- 
ner indicated whenever free sulphuric acid was present in 
the solution that was evaporated. The residue of potassic 
sulphate contains 44.89" [^ of potassium, or 54.08° |g of 
potassa. 

c. The determination of potassium as potaSSic platiuic 
chloride depends upon the insolubility of this compound 
in alcohoh 

The solution being freed from all except potassic and 
sodic chlorides, and, according to Stohraann, calcic and 



§ 44. POTASSIUM. 47 

magnesic chlorides also, and highly concentratei], add 
platinic chloride in excess, until the liquid has a bright 
yellow color, and evaporate the mixture nearly to dryness 
over the water-bath, with care not to heat the water quite 
to boiling. 

Pour alcohol of 84° |^, mixed with ^|g its volume of 
ether, over the residue, let stand several hours in a well 
covered vessel, with occasional stirring, transfer the in- 
soluble double chloride to a dried and weighed filter, 
wash it with alcohol and ether mixed as above directed, 
dry at 100° C, and weigh. 

If great accuracy is required, evaporate the filtrate 
from this first portion of the chloride nearly to dryness, 
at a temperature not above 75° C, after addition of some 
water and more platinic chloride, and some sodic chlo- 
ride if but little of this is supposed to be present, and 
treat this almost dry residue with the mixture of alcohol 
and ether as above ; if a second quantity of insoluble 
chloride is thus obtained, collect it on a filter, wash, dry, 
and weigh it, and add the amount so found to the first 
quantity. 

The salt contains 16"! „ of potassium. 

If the quantity of the precipitate is quite small, less 
than 0.03 grm. or thereabouts, it is better to collect it on 
a small filter, incinerate the filter, add a little pure oxalic 
acid to the cooled residue, cover the crucible, and ignite 
again gently at first, and more strongly afterwards ; after 
tins ignition nothing but platinum and potassic chloride 
remains ; dissolve out the salt by washing the residue 
with water until the washings give no turbidity with ar- 
gentic nitrate, and dry, ignite, and weigh the platinum. 

d. In some cases, as in the analysis of wood-ashes, 
potassium or potassa may be determined by a volumetric 
process, which consists in ascertaining the amount of a 
solution of sulphuric acid of known strength, that is re- 



48 § 45. BxVSES AND ACIDS WITH EEAGENTS. 

quired to combine with it and form a, salt whicli is neutral 
to test-papers (§ 45). 

PREPARATION O^ THE STANDARD ACID AND ALKALINE 
SOLUTIONS. 

45. a. — Sulphuric acid. — To about 1100 c.c. of water 
add nearly 68 grms. of concentrated sulphuric acid, mix 
the whole w^ell togetlier, let the mixture cool to the tem- 
perature of the working room, and then estimate sulphu- 
ric acid with baric chloride (§ 59) in two or three portions 
of 20 c.c. each, with the utmost care ; having in this way 
determined the strength of the solution,- dilute it so that 
one litre shall contain exactly one equivalent of the acid 
expressed in grammes, or 40 grms. Supposing that the 
mean of three satisfactory determinations, as above, gives 
0.84 grm. of sulphuric acid in 20 c.c. : then we learn from 
the proportions, 20 : 0.84 = 1000 : 42, and 40 : 42 = 
1000 : 1050, that 50 c.c. of water must be added to one 
litre of the acid that we have made, in order that it shall 
be of tlie proper strength ; to effect this further dilation, 
measure out 1000 c.c. of the acid in the litre flask, pour 
it without any loss into the bottle in which it is to be 
kept, rinse the Avails of the flask with exactly 50 c.c. of 
distilled w^ater, pour this w^ater likewise into the same 
bottle without loss, and mix the acid and rinsings together 
well ; finally j)our about half the contents of the bottle 
into the flask, rinse off the w^alls of the flask with the 
liquid, and pour it back into the bottle. 

The bottle containing this standard acid should be kept 
well stoppered ; each time that a portion is to be taken 
out, the contents of the bottle should be shaken up in 
such a manner as to rinse down the w^ater that may have 
evaporated in the space above the liquid and condensed on 
the glass. {Fresenlus. Qnantitatwe Chemische Aiudyse.) 

Since 40 is the equivalent of sulphuric anhydride, SO3, 



§ 45. PREPAIIATIOX OF THE STANDARD SOLUTIONS. 49 

and this stiiiidard or iionnal solution contains an equiva- 
lent of the anhydride expressed in grammes, in a litre, 
( = 1000 cubic centimetres) it contains, then, an equivalent, 
expressed in milligrammes, in one cubic centimetre = 40 
mgr. or 0.04 grm. The quantity of acid in one cubic centi- 
metre "^^dll combine with exactly one equivalent of potassic 
oxide or potassa, KoO, expressed in milligrammes, = 47.1 
mgr. or 0.0471 grm., and form a salt whose solution is 
neutral to test-papers ; in a like manner, the acid in one 
cubic centimetre of the standard solution will combine 
with or neutralize one equivalent of sodic oxide or soda, 
!N"a„0, expressed in milligrammes = 31 mgr. or 0.031 grm., 
or with one equivalent of amnionic oxide, (NHJ.O, = 26 
niQ-r. or 0.026 Q^rm. 

The neutrality of the solution may be determined by 
its effect on paper that has been colored by litmus, or by 
adding a small quantity of a solution of litmus, or of 
cochineal or curcuma root. Litmus is colored blue by 
free alkali, and red by free acid ; cochineal under the same 
circumstances is colored purple and light reddish-yellow, 
while curcuma or turmeric is colored brown by free alkali, 
and yellow by acids. 

If, then, to a solution containing any one of the alkalies 
just mentioned, either in a free state or combined with 
the weak carbonic acid, we add a little cochineal solution, 
and then the standard acid from a burette or a graduated 
pipette, with constant stirring, until the ^mrple color sud- 
denly disappears, and a reddish-yellow one takes its place, 
that remains permanent throughout the whole liquid, we 
may know that, for each cubic centimetre of acid added, 
there were 0.0471 grm. of K,0, or 0.031 of ¥a,0, or 0.026 
of (NHJ^O in the solution; the whole amount of the al- 
kali in the quantity of its solution taken for analysis will 
be given by the product of the immber of cubic centime- 
tres of acid required, into the corresponding equivalent 
3 



50 § 45. BASES AND ACIDS WITH EEAGENTS. 

of the alkali, expressed in milligrammes or fractions of a 
gramme as above. 

h. Standard oxalic acid, — Pnt G3 grms. of pure crys- 
tallized oxalic acid in a litre flask, fill the flask np to 
about two-thirds with water, and, after the acid is entirely 
dissolved, add more water until it rises nearly to the mark 
on the neck of the flask ; bring the water to a tempera- 
ture of 15° C, and then, holding the flask by the rim, so 
that it will take a vertical position, carefully add water 
up to the mark on the neck. Mix the whole well together 
by shaking, transfer the liquid to a well stoppered bottle, 
and keep it in a dark place. As 63 is the equivalent of 
crystallized oxalic acid, expressed in grammes, this nor- 
mal solution contains, like the standard sulphuric acid, 
one equivalent of the acid expressed in milligrammes, 
=63 mgr. or 0.063 grm., in one cubic centimetre. 

c. A standard soda solution is often wanted in connec- 
tion with the use of the standard acid, and for other pur- 
poses, and its preparation may be described here. 

It is made of such a strength that one cubic centimetre 
of it will be exactly neutralized by one cubic centimetre 
of the standard acid, or will contain 0.031 grm. of sodic 
oxide, Na.,0. 

To prepare it, put 5 c.c. of the standard acid in a small 
flask with a very little cochineal solution, and then add a 
diluted solution of sodic hydrate, of which a considerable 
quantity has been previously made, from a 5 c.c. pipette 
graduated into twentieths of a cubic centimetre, very 
slowly and with constant shaking of the flask, until the 
reddish-yellow color is just changed to purple ; supj^ose 
that 2 c.c. have to be added ; then evidently 3 c.c. of w^a- 
ter must be added to 2 c.c. of the soda solution, in order 
to make 5 c.c. of the latter that shall exactly neutralize 
5 c.c. of the standard acid; or ^^7"" — tlie amount of 
water to be added to one litre of the sodic solution, to 



§ 46. SODIUM. 51 

make it of the normal strength. When the sohition has 
been prepared according to these directions, and the water 
and alkali are well mixed, it shonld he tested, to be sure 
that the equality between the acid and the alkaline solution 
is perfect. Keep the solution in a bottle closed with a 
cork, through which passes a calcic-chloride tube that is 
stopped at its lower end with a j)lug of cotton and then 
filled with soda-lime ; by this arrangement tlie free ex- 
pansion of the air in the upper part of the bottle with 
clianges of temperature is permitted, while no carbonic 
acid can enter ; it is well to bend the slender part of the 
calcic-chloride tube at a right angle just above the cork, 
so that no soda-lime can possibly fall into the bottle, and 
to fill the burette by means of a small siphon passing 
through the cork to the bottom of the bottle, the longer 
arm of which may be closed at the end by a clamp on a 
rubber tube. 

To 100 c.c. of this solution add 900 c.c. of water, mak- 
ing both measurements with the utmost care, mix well, 
and test this solution with the standard acid ; 1 c.c. of 
the latter should require exactly 10 c.c. of the former to 
neutralize it ; keep this solution in the same manner as de- 
scribed for the other standard soda solution, and labeled, 
^|jg standard soda solution. 

SODIUM. Na. 23. 

46. Salts of sodium, with all the acids named in § 43, 
are soluble in water. The double chloride of sodium and 
platinum is also soluble in both water and alcohol. 

When this solution is very slowly evaporated to dry- 
ness, slender, "rosy, prismatic crystals are formed, while 
the crystals of the corresponding potassium salt are octa- 
hedral and granular. 

Reactions* — When a drop of a solution of a salt of so- 
dium is evaporated to dryness in the platinum-wire loop, 



52 § 46. BASES AND ACIDS AVITH REAGENTS. 

and the loop is then held at the end of the inner blow- 
pipe flame, or in the corresponding part of the flame of a 
Bunsen's gas-burner, a yellow color is communicated to 
the flame beyond the wire. 

These yellow rays are completely absorbed by blue 
glass of suflicient thickness. This test for sodium is very 
delicate, and is not masked by even a considerable ipvo- 
j^ortion of any other metal, except copper and calcium. 
The presence of a very large proportion of potassium 
may conceal the sodium reaction. In that case, green glass 
will absorb the violet rays of the potassium flame, but 
will not aftect the colored rays produced by the sodium. 

Qliantitatiye estimation. — a. Sodium, like potassium, 
may be weighed as chloride or as sulphate, on evaporat- 
ing the solution to dryness, from which all other acids 
except hydrochloric or sulphuric have been removed by 
the methods described in each special case. 

The oj^erations of evaporation and ignition may be 
conducted j)recisely as directed for the treatment of the 
corresponding potassium compounds (§ 44), except that 
no provision need be made to guard against loss by the 
decrepitation of the sodic sulphate. 

Sodic sulphate, N'a.SO^, contains 32.39° |^ of sodium or 
43.66°|„ of soda, l^nfi. Sodic chloride contains 39.32° |„ 
of sodium. 

b. If potassium is present, the two metals being con- 
verted into chlorides, ascertain the amount of the same 
by evaporation to dryness and weighing the residue after 
gentle ignition, as directed for the treatment of potassic 
chloride (§ 44, a), and then determine the amount of po- 
tassic chloride in this mixture, with the aid of platinic 
chloride, as directed under potassium (§ 44, c). The dif- 
ference between the sum of the two chlorides and the 
amount of potassic chloride will give the sodic chloride. 

In this separation, enough platinic chloride must be 



§ 4C. SODIUM. 53 

added to convert T)otli tlic potassimn and the sodium into 
the j^latinic compounds, and the evaporation with platinic 
chloride should not be carried to complete dryness, so as 
to avoid expelling the water of crystallization of the so- 
dic salt. The filtrate from the potassic salt should have a 
deep yellow color, and the salt, when examined with the 
magnifier, should be seen to consist only of yellow octa- 
hedral crystals or a yellow granular powder. 

c. If sulphuric acid is present in the solution containing 
sodium and potassium, the conversion of these metals into 
chlorides may be effected by gentle ignition with powder- 
ed ammonic chloride. Evaporate the solution of the sul- 
l^hates to dryness, mix the residue with a little more than 
its weight of pure ammonic chloride, heat the mixture 
gently as long as fumes are evolved, and weigh ; add more 
ammonic chloride to the contents of the crucible, ignite, 
and weigh again, and repeat this operation as long as 
there is any change in weight. 

d. In case the quantity of one metal in the mixture of 
the chlorides is not ver^ much larger than that of the 
other, they may bo estimated with accuracy by the indi- 
rect process. Determine the chlorine in the known 
weight of the mixture by the volumetric process (§ 63, Z>), 
and then calculate the amount of j^otassium and sodium 
in it by the following formulas, in which S = the Aveight 
of the mixture of the chlorides, and A = the amount of 
chlorine contained therein. 

Potassium = -!-^^ ^ — -* 

U. Oo 

Sodiun^ = A-[(S-A) X 0.91] 
0.63 

e. If it is more convenient to weigh the metals as sul- 
phates, the sulphuric acid may be determined in the usual 



54 § 47. BASES AXD ACIDS WITH REAGENTS. 

maiincr (§ 59), and the respective amounts of sodic and 
potassic sulphate estmiated by the following formulas, in 
which X = the amount of the sodic sulphate, Y that of 
the potassic sulphate, A the weight of the mixed sul- 
phates, and S that of the sulphuric acid contained therein. 

S-(A X 0.45919) 
^ ^ 0.10419. Y - A - X. 

In determining potassium and sodium by either of these 
indirect methods, it is absolutely essential that all other 
metals be carefully removed. 

AMMONIUM. NH4 18. AMMONIA. NH3. 

47. All the salts of ammonium are either volatilized by 
heat or decomposed with expulsion of the ammonia, and 
their solubility is the same as that of the potassium salts, 
except that the tartrate is more soluble. 

Reactions. — Salts of ammonium behave like salts of 
potassium, with platinic chloride, except that when am- 
monic platinic chloride is ignited, nothing but metallic 
platinum is left behind. 

When salts of ammonium are gently heated with baric 
or sodic hydrate, ammonia is expelled and gives a blue 
color to a piece of moistened red litmus-paper held in the 
tube above the liquid, or a brown color to a piece of tur- 
meric-paper. To make this reaction as delicate as possi- 
ble, put the substance to be tested in a small beaker, with 
baric or calcic hydrate in a dry form, moisten the mixture 
with water, cover the beaker with a watch-glass on the 
under side of which is a slip of the moistened test-j^aper, 
and heat the whole gently. Sooner or later, the presence 
of ammonium will be manifested by a change in the color 
of the paper, if any is j^resent in the substance. 

The test is a delicate one, as thus performed, and none 
of the metals interfere with it, if present. 



§ 47. AMMONIUM. 55 

A still more sensitive test is that known as Nessler's. 
When a mixtnre of solution of mercuric iodide in potassic 
iodide, and 2:>otassic hydrate, is added to a solution con- 
taining ammonium, a light or reddish-brown precipitate 
is obtained, NHg J, To make this test still more delicate, 
as in the case of an exceedingly dilute solution of the am- 
moniacal salt, add 25 c.c. of baric hydrate to a litre of 
the water to be examined, distil off '|^ of the mixture, 
and test the distillate with the Nessler solution. 

If the solution is not too dilute, a good reaction is ob- 
tained on holding a drop of the Nessler solution, sus- 
pended on the end of a glass rod, in the test-tube just 
above a mixture of the substance tested and baric hy- 
drate ; if ammonium is present, the drop is colored red- 
dish-brown. 

To make a litre of the solution for this test, and a solu- 
tion that can also be used for quantitative purposes, dis- 
solve 6:2.5 grms. of potassic iodide in 250 c.c. of water, 
and add to this a concentrated solution of mercuric chlo- 
ride, until the precipitated mercuric iodide ceases to be 
dissolved on agitation ; then dissolve 150 grammes of 
caustic potassa in its own weight of water, and add it 
gradually to the iodized mercurial solution, and finally 
the necessary amount of water to make One litre ; let the 
mixture stand 8-10 days, decant the clear and nearly 
colorless liquid, and keep it in well stoppered bottles in a 
dark place. 

Quantitative estimation. — a. Ammonium may be de- 
termined in the form of the ammonic platinic chloride, 
(NHJ^PtClg, when all metals except sodium (and calcium 
and magnesium, Stohmann^ are absent. The course to 
be followed is precisely the same as that described for the 
determination of potassium in the corresponding manner 
(§ 44, c). The double chloride contains .7.64° 1^ of ammonia 
(NH3), or 8.0r |„ of ammonium. 



56 § 47. BASES AND ACIDS WITH EEAGENTS. 

h. Ammonia may also be determined by expulsion 
from the mixture containing it by a strong base, and col- 
lecting the i^roduct in a known quantity of standard acid. 
{Schldssing''s process.) The solution to be examined, 
which should not be more than 35 c.c. in bulk, nor con- 
tain more than 0.3 grm. of ammonia, is put in a shallow 
vessel. A, about 5 cm. in diameter, which, in its turn, is 
put on a plate about 10 cm. in diameter, the bottom of 
which is covered with mercury. Put 10 c.c. of the nor- 
mal sulphuric acid in another, and rather smaller, shallow 
vessel, B, that is supported over A by a glass triangle ; 
then i^ut about 10 c.c. of milk of lime or sodic hydrate in 
A with the ammoniacal solution, by means of a pipette, 
and finally invert a bell-jar or a weighted beaker over 
the whole, and be sure that its rim is completely immers- 
ed in the mercury. 

After 48 hours, the ammonia will usually be entirely 
expelled from the substance, and absorbed by the acid ; 
in the analysis of animal and vegetable liquids, Schulze 
found that three or four days were required, but that after 
the expiration of that time the ammonia was completely 
liberated. To test the matter, lift the edge of the bell- 
jar or beaker, or take out the stopper of the tubulure, if 
the bell-jar has such an appendage, and introduce a piece 
of moistened red litmus-paper ; this should retain its red 
color even if left for a considerable time in the jar. 

If the operation is finished, titrate the acid in the vessel 
B, with the standard solution of soda ; the difference be- 
tween the number of cubic centimetres of acid put into 
B in the beginning, and the number of cubic centimetres 
of soda solution required to neutralize what acid remains 
free, multiplied into 0.017 grm. will give the amount of 
ammonia (NH,) in the substance analyzed — or, multiplied 
into O.O-'^O grm. will give the amount of amnionic oxide 
(NH.),0. 

If albuminoids are jDresent in the substance examined, 



§ 4<. AMMONIUM. 57 

it is better to use freshly ignited magnesia, instead of milk 
of lime, to set free the ammonia, so as to avoid the forma- 
tion of the compound out of a portion of the albuminous 
matters ( Vogel). 

c. When the substance does not contain, besides am- 
monia, nitrogenous organic matter that would yield 
more ammonia on being heated with an alkali, the de- 
termination may be more expeditiously performed as fol- 
lows. 

Weigh the substance out in a small tube about 10 mm. 
in diameter and 5 cm. long, put it in a small flask, A, 
containing a moderately concentrated solution of sodic 
hydrate which has been previously boiled for a consider- 
able time to expel all traces of ammonia, and allowed to 
cool again. Freshly ignited magnesia is sometimes used 
in the place of the alkali. Put the flask in an inclined 
position on the wire gauze over the lamp, and connect it 
quickly with the tube of a small cooling apparatus ; con- 
nect the other end of this tube by a good cork with a 
tubulated receiver, B^ through the tubulure of which 
passes another small tube that is bent twice and carried 
to the bottom of a small flask, C. Put into the receiver, 
JB^ the larger portion of 50 c.c. of standard sulphuric acid 
and the remainder in the flask (7, and color the acid in 
both vessels with a little cochineal; neither tube that 
passes into j5 should dip into the liquid ^'ontained in it. 
Be sure, now, that tlie apparatus is tight throughout, boil 
the contents of the flask A gently, and continue the 
boiling for a little while after the drops of condensed 
liquid as they fall into the receiver have ceased to change 
the color of the acid as they come in contact with it. 
Then remove the lamp, and allow the contents of the 
flask (7 to flow back into B ; rinse C several times with 
cold water, and allow these rinsings to flow into B also ; 
finally disconnect the receiver B from the rest of the 
apparatus, transfer its contents to a beaker Avithout any 
3* 



58 § 47. BASES AXD ACIDS WITH EEAGENTS. 

loss, titrate the acid remaining free with the standard so- 
dic sohition, and estimate the amount of ammonia in the 
substance analyzed, as directed in h. [Fresejiius.) 

d. If the standard acid in either of these processes, 
h or f, should contain but a very small amount of am- 
monia, instead of titrating with soda, the determination 
may be completed more satisfactorily with the aid of the 
Nessler solution, by preparing a solution containing an 
accurately known quantity of ammonia, of such a strength, 
that about equal volumes of it and of the solution con- 
taining the unknown amount of ammonia, will give the 
same shade of color with equal small quantities of this 
reagent. 

The color observations in this process are best made in 
narrow glass cylinders of such a diameter that 100 c.c. of 
the water to be tested form a stratum about 18 cm. deep, 
and by i:>lacing these cylinders upon a sheet of white 
paper near a window and looking at the surface of the 
liquid obliquely. 

The amount of ammonia present in the solution to be 
examined should not be great enough to give a precipi- 
tate with the reagent, but only a coloration ; the best re- 
sults are obtained wlien there is not more than one milli- 
gramme of NH3 in 100 c.c. of the solution, but even if the 
solution is ten times stronger than this, the results are 
more accurate than those obtained by titration ; it is im- 
portant that the temperature of the solution tested sliould 
be nearly the same as that of the other solution contain- 
ing a known quantity of ammonia, which is made the 
standard of comparison, and that neither free potassa or 
soda, nor calcic or magnesic carbonate should be present. 

To estimate the ammonia in a solution by this method, 
first make a standard solution of amnionic chloride con- 
taining 0.3147 grm. in one litre, which is equal to 0.1 
grm. of ammonia (NH3) in the litre; add 1 c.c. of the 



§ 48. BARIU.M. § 49. CALCIUM. 59 

standard iodized mercurial solution to 100 or 150 c.c. of 
the distillate, obtained in b or c, or to any clear and color- 
less solution containing ammonia ; jmt in another test- 
tube, containing about 100 c.c. of water, as much of the 
standard solution of amnionic chloride as is thought nec- 
essary to give the same shade of color with the test- 
liquid, make the volume of this mixture the same as 
of the other, by addition of water, add 1 c.c. of the 
iodized mercurial solution, let stand ten minutes, and then 
compare shades of color ; if not alike, make another more 
or less diluted portion of the standard ammonic solution, 
according as the shade of color of the first was too dark 
or too light, and repeat the test.. ( W. A. Miller.) 

BARIU.^r. Ba. 137. 

48. Compounds o- barium with sulj^huric, oxalic, car- 
bonic, phosphoric, tartaric, and silicic acids, and with flu- 
orine, are insoluble or sparingly soluble in water. The 
sulphate and silicate are insoluble in acids. 

Reactions. — Sulphuric acid and all soluble sulphates 
produce, even in very dilute solutions of barium salts, a 
finely pulverulent ^^I'ecipitate of baric sulphate, BaSO^, 
insoluble in acids, except when hot and concentrated, and 
even then but very sparingly soluble. This sulphate is 
slightly decomposed when boiled with a solution of sodic 
carbonate, but is not changed at all if a soluble sulphate 
is mixed with the carbonate. 

CALCIUM. Ca. 40. 

49. Compounds of calcium with oxalic, carbonic, phos- 
phoric, tartaric, and silicic acids, and with fluorine, are 
insoluble or sparingly soluble in water. The tartrate dis- 
solves in 352 parts of boiling water. The silicate and 
fluoride are insoluble in acids. Both water and acids dis- 
solve the sulphate in small quantity. 



60 § 49. BASES AND ACIDS AVITH REAGENTS. 

ReactionSi — If dilute sulphuric acid or amnionic sul- 
phate is added to a not too dilute solution of a calcic salt, 
free from a large excess of strong acids, a white precipi- 
tate of calcic sulphate, CaSO^, ^^fi, is formed immedi- 
ately or after standing some time, which is soluble in an 
excess of mineral acid, and slightly soluble in acetic acid 
and water. 

This sulphate being mu'ch less soluble in alcohox than 
in water, the addition of a quantity of this reagent about 
equal to the volume of the solution, will often cause the for- 
mation of a precipitate, at least after standing some time, 
that would otherwise not appear. 

This i^recipitate is readily decomposed when boiled 
with a solution of sodic carbonate, calcic carbonate and 
sodic sulphate being formed. 

Ammonic oxalate gives, even in very dilute solutions 
of calcic salts, if they contain no free mineral acid, a 
white crystalline precipitate of calcic oxalate, CaC^O^, 
soluble in hydrochloric or nitric acid, and insoluble in 
acetic acid or a solution of ammonic chloride. If the so- 
lution of the calcic salt is very dilute, a precipitate may 
not appear until after the mixture has stood some time. 

QuantitatiYC Estimation. — Calcium is usually deter- 
mined as carbonate, CaCOg, by precipitation with am- 
monic oxalate and conversion of the oxalate into carbon- 
ate by ignition. 

a. 1 • — If the salt is soluble in water or the acid is one 
that, like carbonic acid, may be expelled by hydrochloric 
acid, or can be removed by evaporation to dryness, like 
silicic acid, or the solution gives no precipitate with am- 
monia, add ammonic oxalate to the hot solution free from' 
any great excess of acid, and then ammonic hydrate until 
the liquid, after being well stirred, gives off an ammoni- 
acal odor, let the mixture stand in a warm place 12 hours, 
decant the clear liquid into a filter, wash the precipitate 



§ 49. CALCIUM. 61 

several times by decantation, and finally rinse it into the 
filter with hot water. Ignite the precipitate and filter 
separately (§ 40, b), keeping the filter-ash on the crucible 
cover. Keep the crucible at a faint red heat 5 or 10 
minutes at the close of the ignition ; at no time should it 
be heated to a higher temperature than this ; during this 
short ignition lift the cover of the crucible a few times. 

After weighing, moisten the contents of the crucible 
w^ith a little water and apply a piece of turmeric-paper 
to the moist mass ; if the paper is turned brown, rinse it 
oif with a very small quantity of water, put a small 
lump of ammonic carbonate into the crucible, heat tlie 
crucible over the water-bath until its contents arc dry 
again, ignite gently, and w^eigh again ; re^^eat this opera- 
tion wath fresh portions of ammonic carbonate, and igni- 
tion, as long as there is any change in weight. The 
change of color in the turmeric-paper showed that the 
first ignition was carried too far, so as to expel some of 
the carbonic acid, and leave calcic oxide. {Fresenius.) 

The residue of calcic carbonate contains 40 °|^ of calci- 
um or 56 "Ig of calcic oxide or lime. 

2. If a blast-lamp is at hand, or a gas blow-pipe, it is 
best to ignite the precipitate of calcic oxalate 10 minutes 
to an incipient white heat, after the usual ignition to a red 
heat over the common lamp ; in this w^ay all the calcic 
carbonate will be converted into calcic oxide, which may 
be weighed as such ; no testing of the ignited residue is 
necessary, and moreover the filter may be burned wath 
the precipitate. 

3. Instead of igniting the precipitate of ammonic oxa- 
late, after it has been well washed in the usual manner, 
dissolve it in dilute hydrochloric acid Avhile yet moist, 
add water in such a quantity that the ratio between the 
oxalic acid and the water will be about 1 : 400 or 500, 
add to this 6-8 c.c. of concentrated sulphuric acid, and 
then estimate the oxalic acid in this solution with the aid 



62 50. BASES AXD ACIDS WITH liEAGENTS. 

of the standard permanganate solution, as directed in 
§ 69, a. This method yields results that are hardly less 
accurate, if any at all, than the other two already de- 
scribed. For each equivalent of oxalic acid found, ex- 
pressed in milligrammes^ reckon one equivalent of lime, 
similarly expressed, or 0.028 grm. 

If the amount of calcic oxalate in the filter is very 
small, it may he converted into sulphate by ignition witli 
pure ammonic sulphate, and the lime weighed as sulphate, 
containing 41.18 "|^ of lime. 

h. If the acid in combination with the lime is one that, 
like phosphoric acid, cannot be readily removed, add am- 
monia until a permanent precipitate just begins to appear, 
dissolve this by adding a few drops of hydrochloric acid, 
add amm.onic oxalate in excess, then sodic acetate, and 
proceed as in a with the precipitated calcic oxalate. 

MAGNESIUM. Mg-. 24. 

50o Compounds of magnesium with phosphoric, car- 
bonic, oxalic, and silicic acids, and with fluorine, are in- 
soluble or sparingly soluble in water. The silicate and 
fluoride are insoluble in acids. 

Reactions. — The carbonate is not j^recipitated from so- 
lutions of magnesic salts containing much ammonic chlo- 
ride, on addition of an alkaline carbonate. 

Hydric disodic phosphate produces a white precipitate 
of ammonio-magnesic phosphate, MgNH^PO^, in solutions 
of magnesic salts containing ammonic salts. The precipi- 
tate, at first flocculent, if at all abundant, becomes more 
granular and crystalline after standing some time, or after 
violent agitation of the liquid containing it. If the solu- 
tion of the magnesic salt is very dilute, the precipitate 
may not appear for some hours, and then it is crystalline 
and adheres to the sides of the tube ; if, before the solu- 
tion was set aside, it was stirred with a glass rod, and the 



50. MAGNESIUM. 63 

walls of the tube nibbed here and there Avith the rod, the 
precipitate is deposited along these lines, producing the 
appearance of white streaks on the glass. 

Even in concentrated solutions containing magnesium 
and ammonic chloride and sodic phosphate, the whole of 
the ammonio-magnesic phosphate is not deposited until 
after long standing; hence, if the first precijoitate pro- 
duced on adding the reagent is filtered out, and the clear 
filtrate stirred and set aside, a fresh precipitation will take 
place, and partly on the walls of the tube in the manner 
described above. 

Quantitative estimation. — Magnesium is usually deter- 
mined as pyrophosphate, Mg.P^O^. * 

a. To the solution of the magnesic salt add a consider- 
able quantity of ammonic chloride, and then ammonia in 
slight excess ; if this ammonia causes the formation of a 
precij^itate, add enough more ammonic chloride to dis- 
solve it ; then add hydric disodic phosphate, as long as a 
precipitate is formed, stir the mixture well, with care not 
to touch the sides of the beaker Avitli the rod, cover the 
beaker carefully, and let it stand with its contents 12 
hours without applying heat ; decant the clear liquid 
through the filter, rinse the contents of the beaker into 
the filter with portions of the first filtrate, and wash the 
contents of the filter with a diluted ammonia water 
containing one part of ammonia water of 0.9G Sp. Gr. 
and three of water, until the last five drops of the wash- 
ings give no opalescence w^ith very dilute nitric acid con- 
tainino* aro-entic nitrate. 

Ignite the precipitate and filter separately. Rose rec- 
ommends to ignite the precipitate for a short tinj[;^ in a 
porcelain crucible over the blast-lamp ; in this way it is 
obtained quite white. 

Add 0.002 grm. to the residue of magnesic phosphate 
for every 110 c.c. of the filtrate from the precipitate (but 



64 50. BASES AND ACIDS WITH REAGENTS. 

not the Avasbings), to compensate for the solubility of the 
salt in the ammoniacal solution in which it was preci^^i- 
tated. {Fresenlus.) 

Tlie residue contains 36.04" |^ of magnesic oxide or 
magnesia, MgO. 

If the solution containing the magnesium is strongly 
acid, Rose recommends that the sodic phosphate be added 
first, and then a sufficient -quantity of ammonia to super- 
saturate the acid ; thus he prevents the formation of any 
hydrated magnesic oxide that is liable to be precipitated 
with the phosphate and make it impure. 

h. Separation of Calcium and Magnesium. — This is 
eifected with ammonic oxalate in the presence of am- 
monic chloride, and ammonia in slight excess. Add the 
ammonic chloride and ammonia as directed above in < ', 
and then ammonic oxalate ; this last reagent must be 
added in slight excess, after it has ceased to give any 
further precipitate of calcic oxalate, in order to convert 
all the magnesium into oxalate. Let the mixture stand 
12 hours in a moderately warm place, decant the clear 
liquid into the filter, wash the precipitate in the beaker 
once with water, decant the washings, dissolve the pre- 
cipitate in a little dilute hydrochloric acid, add ammonia 
in slight excess, and ammonic oxalate ; let the mixture 
stand until the precipitate has completely subsided, then 
filter through the same filter as before, and wash. Tlie 
first filtrate has the larger portion of the magnesium in 
it ; the second, the rest. 

Acidify the second filtrate, and concentrate that and 
the washings by evaporation, add the residue to the first 
filtrate, and precipitate magnesium in this solution as 
phos^ate. Treat the precipitate of calcic oxalate on the 
filter as directed in § 49. 

If, in the filtrate from the calcic oxalate, there is a 
great excess of ammonic salts, it will be safer to evapo- 
rate the solution to dryness and expel them by ignition, 



§ 51. ALUMINIUM. 05 

dissolve the residue in water acidified with hydrochloric 
acid, filter if necessary, and then to precipitate the mag- 
nesium in the usual manner with hydric disodic phosphate. 

c. If but little calcium is mixed with considerable mag- 
nesium in the substance to be analyzed, evaporate the 
solution to dryness, and ignite the residue gently to ex- 
pel ammoniacal salts completely, dissolve this residue in a 
very little water mixed with a few drops of hydrochloric 
acid, add strong alcohol and a slight excess of pure con- 
centrated sulphuric acid, and digest the mixture in the 
cold several hours. Collect the precipitated calcic sul- 
phate on the filter, wash it first witli almost absolute al- 
cohol and finally with alcohol of about 40 °|^, dry, ignite 
and weigh. 

Expel the alcohol from the filtrate and washings by 
heat, and determine magnesium in the usual manner with 
sodic phosphate. 

ALUMINIUM. Al. 27.5. 

51, Compounds of aluminium with phosphoric and 
silicic acids, and fluorine, are insokible in water. The 
silicate is insoluble in acids. 

Reactions. — Solutions containing aluminium give a pre- 
cipitate, A1,03,3H„0, or AlJigO^, with ammonic or sodic 
hydrate ; the precipitate is dissolved in an excess of the 
latter reagent, but not in the former. 

When a compound of aluminium is fused on platinum 
foil with four or five times its bulk of sodic and potassic 
carbonate, the fused mass dissolved in a very little water, 
and the solution filtered if necessary, nitric acid added to 
the filtrate carefully until efiervescence ceases, and then a 
few drops of ammonia until tlie solution emits a fiiint 
odor of the reagent, a white flocculent precipitate appears, 
at once, or after standing some time ; it will appear soon- 
er, or be more readily perceived, on heating the liquid 
gently for a time. 



63 5,2. BASES AXD xVCIDS WITH EEAGE^^TS. 

QuailtitatiTC estimation. — Aluminium is always weigh- 
ed as sesquioxide, Al„03. 

To the not too dilute hot solution add a fourth or a 
third of its volume of ammonic chloride, if not already 
present, and then ammonic hydrate until a faint odor of 
ammonia is perceptible after vigorous stirring ; heat the 
mixture almost to boiling until no more ammonia is given 
off, let it stand a few hours in a moderately warm place, 
decant the clear liquid through the filter, wash the pre- 
cipitate two or three times with hot water, by decanta- 
tion, transfer the whole to the filter, and wash it until the 
washings leave no fixed residue on platinum foil ; if the 
solution contained sulphuric acid in notable quantity, it 
will be best to dissolve this first precipitate in dilute hy- 
drochloric acid, and re-precipitate the aluminic hydrate 
with ammonia, as above. Dry the precipitate very thor- 
oughly, and ignite it gently at first, and carry the heat to 
a full red, finally. 

The residue is pure alumina. 

IRON. Fe. 56. 

52. Compounds of iron with carbonic, phosphoric, 
oxalic, and silicic acids, and sulphur, are insoluble in water ; 
the silicate is insoluble in acids. 

Ferric salts give a yellowish-red color to solutions con- 
taining them in notable quantity. 

Reactions. — Solutions of ferrous and ferric salts give 
precipitates, FeO, H^O, or Fetl^O, and 2Fe.fi^, 3H^0 or 
Fe^HgO^, with ammonic or sodic hydrate ; the ferrous salts, 
however, give no precipitate with ammonia in the presence 
of ammonic salts. These precipitates are insoluble in ex- 
cess of the precipitant. The precipitate produced in so- 
lutions of pure ferrous salts is white j in solutions of 
ferric salts, reddish-brown. 

Solutions of ferrous salts give a blue precipitate with 



§ 52. iKoiM. 67 

potassic ferricyanide ; ferric salts give no precipitate with 
this reagent. 

Ferric salts give a deep red color with potassic sulplio- 
cyanate ; this reaction is exceedingly delicate. Nitric 
acid causes the color to disappear after a Avhile, and am- 
nionic hydrate destroys it immediately. Ferrous salts 
give no color with this reagent. 

Ferrous salts are converted into ferric compounds when 
heated with nitric acid. 

Quantitative estimation,— Iron may be determined by 
a gravimetric or a volumetric process. In tlie former 
case it is Aveighed as sesquioxide, Fe^O^. 

a. Add amnionic hydrate in excess to tlie hot solution, 
in which the iron has been completely oxidized by heating 
with nitric acid, if any ferrous oxide was present, heat 
the mixture almost to boiling, and then let it stand until 
the larger part of the liquid can be decanted into the fil- 
ter ; wash the precipitate several times by decantation, 
and afterwards on the filter, until a droj) of the washings 
leaves no residue on evaporation on platinum foil, and 
ignite the precipitate and filter separately. The residue 
is pure ferric oxide, and contains 70"! ^ of iron. 

If the substance analyzed contained silica, this precipi- 
tate is liable to be contaminated with it, and should be 
digested with concentrated hydrochloric acid, after hav- 
ing been gently ignited ; if silica is present, it will remain 
undissolved, and may be filtered out and weighed. 

h. The volumetric process, with potassic permanganate, 
is particularly convenient for the determination of iron 
in the presence of aluminium. The iron is converted into 
a ferrous salt, and then it is ascertained how much of a 
solution of permanganate of known strength is required, 
to oxidize the ferrous to a ferric salt. 

To make the solution of permanganate, dissolve about 
8 grms. of the crystallized potassic permanganate of the 



68 § 52. BASES A^•D acids with reagents. 

druggists in one litre of water ; as this solution is changed 
by exposure to the air, its strength must be determined 
from time to time, and the oftener, the more imperfectly 
it is protected from such exposure. 

To determine its strength, weigh out accurately about 
1.4 grms. of ammonio-ferrous sulphate, dissolve the salt 
in about 200 c.c. of distilled water, to which about 20 c.c. 
of dilute sulphuric acid have been added. To protect the 
salt more completely from oxidation while the solution is 
taking place, heat it with a part of the water in a small 
flask closed by a cork through which two short glass 
tubes pass ; fasten the flask in an inclined position in a 
retort-holder, and heat its contents while a slow current 
of carbonic acid is conducted through the upper part of 
it. When the solution is completed, let the liquid cool in 
the current of carbonic acid, transfer it quickly to a beak- 
er or a larger flask, rinse the flask out with the rest of 
the water, set the vessel over white paper, and immedi- 
ately begin to add the solution of permanganate from a 
burette, with constant stirring of the liquid. At first, 
the red drops disappear the instant that they come in 
contact with the solution, and the latter gradually takes 
a yellowish tint ; add the j^ermanganate more and more 
carefully as the drops begin to disappear less readily, and 
stop when the last drop gives an unmistakable reddish 
color to the whole liquid. 

Ammonio-ferrous sulphate contains just one-seventh of 
its weight of iron, and hence the amount of ^permanganic 
solution used in this trial will convert a weight of 
iron from ferrous to ferric oxide, equal to one-seventh of 
the weight of the salt taken. 

The concentration of the solution of permanganate 
should be such, that from 20 to 30 c.c. is required for 1.4 
grms. of ammonio-ferrous sulphate, or 0.2 grm. of metal- 
lic iron. 

Now, to determine iron by this process the ferric salt 



§ 52. IRON. 69 

must be in the form of a sulphate or a chloride, and the 
solution should contain about 0.5 grm. of iron and an 
excess of free sulphuric or hydrochloric acid and as little 
nitric acid as possible ; heat the solution in a small, long- 
necked flask placed in an inclined position, drop in a few 
pieces of pure zinc, and conduct carbonic acid through 
the flask in the same manner as described above, for dis- 
solving the ferrous salt ; the ferric compound is reduced 
to a ferrous salt by the zinc, with the evolution of hydro- 
gen. When the solution is decolorized, and all the zinc 
is dissolved, cool the liquid as quickly as possible by im- 
mersing tlie flask in cold water, while carbonic acid is 
still passing through, transfer the solution to a beaker, 
rinse the flask into the beaker with a considerable quanti- 
ty of water, and dilute the solution until it contains about 
200 c.c. for every 0.2 grm. of iron supposed to be present ; 
the solution must be more largely diluted if the salt was 
a chloride, or was dissolved in hydrochloric acid, instead 
of sulphuric. 

To this solution add the solution of permanganate in 
the same manner as directed above, for the treatment of 
the ferrous salt. 

The amount of iron m the quantity of solution taken 
will be given by the proportion 

C : F = C^ : X 
7 
in which C = the number of cubic centimetres of per- 
manganic solution used in the trial with the known quan- 
tity of ferrous salt, F = the weight of the ferrous salt 
taken, C^ = the number of cubic centimetres of perman- 
ganic solution used in the trial with the substance exam- 
ined, and X = the amount of iron therein. 

The solution of potassic permanganate is most con- 
veniently kept in a bottle provided with an ordinary 
washing-bottle arrangement for filling the burette from 
it • then the bottle need not be opened until empty, no 



70 52. BASES AND ACIDS WITH llEAGENTS. 

dust can get into it, particularly if the open end of the 
shorter tube is closed with a plug of cotton, and its 
strength will not change perceptibly in two or three 
months. 

c. The following volumetric method of estimating fer- 
ric oxide has given satisfactory results ( Oudetnans^ Fre- 
sejiius's Zeltschrift^ G, 129), and is very easily executed. 

Prepare a standard solution of sodic hyposulphite, by 
dissolving 24.8 grms. of the pure crystallized salt in one 
litre of water ; this gives a ' ],„ normal solution, since 248 
is the equivalent of the crystallized salt. Determine the 
strength of a solution of ferric chloride containing no 
traces of free chlorine, as carefully as possible, by precipi- 
tation with ammonia {a). 

To a quantity of this solution, accurately measured, 
containing about 0.2 grm. of iron, add a little hydrochlo- 
ric acid, one or two drops of a concentrated solution of 
cupric sulphate, and the same quantity of potassic sulpho- 
cyanate ; heat this blood-red liquid to about 40° C, and 
allow the standard solution of hyposulphite to flow from 
a burette into it with constant stirring, until the red color 
disappears, leaving a clear, colorless liquid ; towards the 
end of the operation, when the color of the solution has 
become quite pale, wait a few seconds between each ad- 
dition of a few drops of the hyposulphite. Divide the 
quantity of ferric oxide corresponding to the amount of 
ferric chloride taken, by the number of cubic centimetres 
of the solution of hyposulphite required in this trial, and 
the quotient will give the amount of ferric oxide which 
the sodic liyposulphite in one cubic centimetre of the 
standard solution is able to reduce to protoxide. 

Having in this way determined the value of the solu- 
tion of hyposulphite with reference to ferric oxide, this 
oxide may be determined in any solution containing it or 
the corresponding chloride, in the manner described 



§ 53. MANGANESE. 71 

above ; the solution should contain no free chlorine or ni- 
tric acid. 

The standard solution of liyposulphite should be care- 
fully protected from the light, and the determination of 
its strength should be repeated from time to time by com- 
parison with a portion of the solution of ferric chloride 
of known strengtli, as above. 

MANGANESE. Mn. 55. 

53. Compounds of manganese with phosphoric, car- 
bonic, oxalic, and silicic acids, and sulphur, fluorine, and 
cyanogen, are insoluble or sparingly soluble in water. 
The silicate is insoluble in acids. 

Reactions. — A solution containing manganese gives a 
precipitate, MnO,H„0, or MnH„0„, with sodic or amnionic 
liydrate ; the presence of amnionic chloride prevents tlie 
formation of the precipitate by amnionic hydrate ; in this 
way manganese may be partially separated from iron for 
qualitative purposes. 

When a compound of manganese is fused with potassic 
and sodic carbonate and sodic nitrate, the fused mass 
takes a bluish-green color, which can be masked only by 
the presence of a very considerable quantity of iron. In 
case this large proportion of iron is present, it may be 
precipitated by ammonia after adding considerable am- 
monic chloride, filtering it out quickly, and evaporating 
the filtrate ; then test a few drops of the concentrated 
liquid by fusion, as above. 

Quantitative estimation. — The manganese is usually 
precipitated as carbonate ; when ignited, this carbonate is 
converted into manganous manganic oxide, Mn^O^, which 
is weighed. Heat the solution, free from any great excess 
of mineral acid, nearly to boiling in a capacious flask, add 
sodic carbonate very slowly until it is in excess, boil a few 
minutes, and wash the precipitate by decantation and on 



72 § 54. BASES AND ACIDS WITH REAGENTS. 

the filter; ignite the filter and its contents separately. 
The ignition should be carried to a full red heat. The 
residue contains 72.05" |g of manganese. 

ZINC. Zn. Go. 

54. Compounds of zinc with phosphoric, carbonic, ox- 
alic, and silicic acids, and sulphur and cyanogen, are in- 
soluble or sparingly soluble in water. The silicate is 
insoluble in acids. 

Reactions* — Solutions of zincic salts give a white pre- 
cipitate, ZnO, IT„0 or Znll^O,, with sodic or ammonic 
hydrate, soluble in excess of the precipitant, and re-pre- 
cipitated from this solution on dilution with considerable 
water and boiling. 

Solutions of zincic salts give a white flocculent precipi- 
tate, Zn^Fe^Cy^, with potassic ferrocyanide, that is difii- 
cultly soluble in acids. 

LEAD. Pb. 207. 

55. Compounds of lead with sul23huric, phosphoric, car- 
bonic, oxalic, and tartaric acids, and sulphur and fluorine, 
are insoluble, or sparingly soluble in water. The sulphate 
and sulphide are insoluble in dilute acids. 

Reactions. — Solutions of salts of lead give a white pre- 
cipitate, 2PbO, H„0 or Pb^H^Og, with sodic or ammonic 
hydrp,te, insoluble in excess of the precipitant. 

If free from a very large excess of strong acid, they 
give a white precipitate, PbSO^, with dilute sulphuric 
acid, which appears at once, or after some time if the so- 
lution is very dilute ; this precipitate is insoluble in dilute 
acids, and is more insoluble m dilute sulphuric acid than 
in pure water ; it is soluble in a solution of ammonic tar- 
trate containing an excess of ammonia; if this solution 
is acidified with acetic acid and potassic dichromate add- 



§ 56. COPPER. § 5T. ARSENIC. 73 

ed, a ycUoAV precipitate of plumbic chromate, PbCrO^, is 
formed. 

Lead is precipitated from its solutions by metallic zinc 
in the presence of free acid. 

COPPER. Cu. 63.5. 

56. Compounds of copper with phosphoric, oxalic, car- 
bonic, tartaric, and silicic acids, and sulphur and cyanogen, 
are insoluble, or sparingly soluble in water. The sulphide 
and silicate rtre insoluble in dilute acids. 

Cupric salts give a blue or a greenish-blue color to so- 
lutions containing them. 

Reactions.— Solutions containing copper give a green- 
ish precipitate, CuO, H^O or CuH^O,, with sodic or am- 
nionic hydrate. This precipitate is dissolved by an excess 
of ammonic hydrate, giving a deep blue solution ; the 
reaction is very delicate. 

Solutions of copper give a red precipitate with potassic 
ferrocyanide, Cu^jFe^Cyg. 

Copper is precipitated from its solutions by zinc in the 
presence of free sulphuric or hydrochloric acid; free 
nitric acid hinders the reduction, but does not prevent it. 

ARSENIC. As. 75. 

57. When a solution containing arsenic is treated with 
dilute sulphuric acid and metallic zinc, in a small flask 
closed with a cork through which passes a glass tube 
drawn out to a small jet at the end, and the escaping gas 
is lighted, after it has heen evolved long enough to expel 
the oxygen from the flask, a bluish flame is produced, 
which deposits black, shiny spots on a cold porcelain sur- 
face. The arsenic was evolved as arseniuretted hydrogen, 
ASH3. This reaction is very delicate, and is known as 
Marsh's test. 
4 



74 § 58. BASES AND ACIDS WITH EEAGENTS. 

ACIDS. 
SILICIC ACID. HsSiOa. 

58. All silicates are insoluble in water and dilute acids, 
except those of potassium and sodium. 

Silicates may be decomposed, and the metals contained 
in them brought into a soluble form, by means of concen- 
trated hydrochloric or sulphuric acid, by hydrofluoric acid 
or ammonic fluoride, or by fusion with an alkaline carbon- 
ate, and subsequent treatment with dilute hydrochloric 
acid. 

Reactions. — If a solution of a soluble silicate is evapo- 
rated to dryness, after addition of hydrochloric acid, the 
residue gently ignited and treated \vith dilate acid, the 
silica remains undissolved in the form of a white, gritty 
powder. 

When a silicate in powder is fused in a bead of sodic 
carbonate, on platinum wire, the carbonic acid is expelled 
by the silicic, and its evokition causes the bead to froth. 

If a very small fragment of an insoluble silicate is 
fused in a bead of phosphorus-salt, on platinum wire, 
the bases are dissolved out, and the silica remains floating 
about in the bead, retaining the form of the original 
fragment. 

Quantitative estimation. — Silicic acid is always Aveighed 
as such. 

a. 1, — If the acid is to be determined in a solution or 
a soluble silicate, add an excess of hydrochloric acid to 
the solution, or the very finely jDOwdered solid, and 
evaporate the mixture to dryness on the water-bath with 
frequent stirring to break up the lumps. 

If, as is sometimes the case, the solution analyzed con- 
tains organic matter, or ferrous oxide, add a few drops of 
nitric acid towards the close of the evaporation. If a solid 
is being treated, the digestion should be continued, with 



§ 58. SILICIC ACID 75 

the addition of fresh quantities of acid if necessary, until no 
gritty particles can be felt under the end of the stirring 
rod. Heat the residue to a temperature somewhat above 
100°, in an air-bath, made by suspending the dish on wires 
inside of an iron dish, so that there shall be a space of 
about 12 mm. between the two at all points ; when the 
whole is completely dry and no more acid fumes escape, 
moisten the residue with concentrated hydrochloric acid, 
let it stand half an hour, add water, and digest the mix- 
ture awhile, wash the insoluble residue two or three times 
by decantation, wash well on the filter, dry, and ignite. 
The residue is generally pure silicic acid. 

All the bases with ^vhich the silica was combined can 
be determined in the filtrate from it. 

2. Sometimes this residue is mixed Avith sand which it 
may be desired to estimate. 

In this case collect the mixture on a dried and weighed 
filter, dry it at 100° C, and weigh it ; then separate it 
from the filter as completely as 2:)ossible without tearing 
the latter, and boil it with several portions of a concen- 
trated solution of sodic carbonate, or with sodic carbonate 
to which about '|^ of sodic hydrate has been added, or 
with sodic hydrate alone ; dilute each jDortion of the 
liquid if it contained much free alkali, let it cool, and 
throw^ it on the same filter from which the mixture of 
silica and sand was taken ; finally, transfer the insoluble 
sand to the same filter, w^ash it well, dry, and ignite. If 
the extraction of the silica was performed in a silver dish, 
the amount taken into solution by the alkaline liquids 
may be estimated also ; for this purpose, evaporate all the 
filtrates and washings to dryness, after having added an 
excess of hydrochloric acid, and determine the silica as 
in a. 

3, Sometimes, in agricultural analyses, this residue con- 
tains, besides silica and sand, free carbon, or coal. In 
this case, dry the whole at 100° and weigh it, separate it 



76 § 58. BASES AND ACIDS WITH KEAGENTS. 

from the filter as above, treat it with the alkaline solu- 
tions also in the same manner, collect the residue that is 
insoluble in the alkali on a dried and weighed filter, dry 
and weigh it, and finally ignite and weigh again. The 
first of the three weighings gives the total amount of 
silica, sand, and coal, the second the sand and coal, and 
the third the sand alone. 

5. If the silicate is insoluble in water or acids, pulverize 
it until an impalpable powder is obtained, mix a weighed 
quantity of it, in a platinum crucible, with four parts of 
finely powdered potassic sodic carbonate, as intimately as 
possible by stirring with a glass rod ; wipe the glass rod 
Avith a little more of the carbonate on a slip of glazed 
paper, and transfer this from the paper to the crucible ; 
the latter should not, with all its contents, be more than 
two-tbirds filled. Cover it well and heat at first moder- 
ately over a blast-lamp, or, after imbedding it in calcined 
magnesia in a Hessian crucible, in a furnace ; carry the 
heat gradually to an intense red ; after about 20 minutes 
the mass will have ceased to boil and bubble, and the 
operation is finished. Put the crucible, when cold, into a 
beaker with considerable water, and add hydrochloric 
acid gradually, as directed for the solution of carbonates, 
§ 36 ; when the mass is entirely loosened from the cruci- 
ble, take the latter out, rinse it carefully into the beaker, 
transfer the contents of the beaker to a platinum or a 
porcelain dish, evaporate to dryness, and eliminate silicic 
acid, as in a. 

c. Of course j^otassium and sodium cannot be deter- 
mined in the filtrate from the silica in h, since both metals 
have been added to the substance in a large and undeter- 
mined quantity. 

For the determination of these elements the silicate 
must be decomposed with the aid of hydrofluoric acid or 
a fluoride. 



§ 58. SILICIC ACID. 77 

1. Decomposition with hydrofluoric acid. — Provide a 
leaden cup about 16 cm. in diameter and 16 cm. deep 
with a close-fitting cover, with j^rojections on the sides 
about 8 cm. from the bottom, supporting a perforated 
shelf, and with a shallow tray in the bottom about 12 cm. 
in diameter and 3 cm. deep, all made of lead ; spread a 
layer of finely powdered fluor spar about 12 mm. deep, 
over the bottom of the tray in the cup, and mix it with 
enough concentrated sulphuric acid to make a thin paste ; 
put the shelf in its place and on the shelf a shallow plat- 
inum dish, such as a crucible cover, containing 1-2 grms. 
of the very finely j^ulverized and carefully weighed sub- 
stance, spread over the surface of the dish in as thin a 
layer as possible and moistened with sulphuric acid ; 
put the cover on the cup, and set it in a warm place 
where the temperature is about 60° or 70° C, and lift 
the cover a few times in the course of the digestion ; 
the evolution of the hydrofluoric acid should be main- 
tained all the time. After 48 hours take the substance 
out, expel most of the sulphuric acid by heat, boil the 
residue with dilute hydrochloric acid, and, if anything 
remains undissolved, treat this residue with hydrofluoric 
acid in the same manner as above described. The 
alkaline metals can be determined in this solution by 
hydrochloric acid. 

2. Decomposition by ammonic fluoride, — This method 

is considered by many to be easier of execution and more 
certain in its results than the other. Mix the very finely 
pulverized silicate with 4-5 times its weight of ammonic 
fluoride in a platinum dish, moisten the mixture thorough- 
ly with concentrated sulphuric acid, and heat the whole 
on the water-bath in a place where the fumes of hydro- 
fluoric acid will be carried ofi" speedily; after a time, 
when the evolution of acid fumes has ceased, moisten the 
residue again with sulphuric acid, and heat it, directly 
over the lamp at last, until it is completely dry and all 



78 . § 59. BASES AND ACIDS WITH REAGENTS. 

tlie sulphuric acid is expelled ; digest the residue with 
hydrochloric acid ; it should be dissolved completely, 
although, if calcium is present, considerable time may be 
required. If the solution is not complete, the insoluble 
jDart should be treated again with amnionic fluoride. 

SULPHURIC ACID. II2SO4. 

59» The sulphates of lead, barium, and calcium, are in- 
soluble, or difficultly soluble, in water and dilute acids ; 
the last of the three is much the most soluble. 

Reactions. — Sulphuric acid and solutions of sulphates 
give a finely pulverulent precipitate, BaSO^, with baric 
chloride, insoluble in water or dilute acids ; the reaction 
is very delicate. 

Quantitative estimation. — This acid is always de- 
termined as baric sulphate, BaSO^. Heat the slightly 
acid solution nearly to boiling, and add a hot solution 
of baric chloride as long as a precipitate is formed ; 
let the mixture stand until the precipitate settles, and 
wash the latter by decantation, until the washings 
give no reaction for barium with sulpliuric acid ; then 
pour 40 or 50 c.c. of the solution of cupric acetate 
(§ 9) over the precipitate in the beaker, add some water 
and so much acetic acid that, after digestion for 10 
or 15 minutes at a temperature very near to boiling, no 
basic cupric salt separates from the solution ; if any does 
appear, dissolve it by adding more acetic acid ; stir the 
mixture constantly during the digestion. Filter, wash 
the precipitate with hot water, and, if the filter is still 
colored blue, moisten it with a little dilute hydrochloric 
acid and wash with more water, until the washings give 
no reaction for copper Avith potassic ferrocyanide. Ignite 
the precipitate and filter separately. The residue con- 
tains 34:.dVl of sulphuric anhydride, SO3, or 13.73" |„ of 
sulphur. 



60. CARBONIC AGIO. 



9 



Unless the precipitated baric sulphate is washed, as 
above directed, with a solution of cupric acetate, the re- 
sult of the analysis may be very unreliable, particularly 
if notable quantities of nitrates or alkaline salts were 
present. 

CARBONIC ACID OR ANHYDRIDE. CO^. 44. 



60. Carbonates of all except the alkaline metals are 
insoluble, or sparingly soluble in water; all carbonates, 
without exception, are dissolved by dilute acids, with the 
expulsion of carbonic anhydride, CO^. 

Reaction. — When dilute nitric or hydrochloric acid is 
added to a carbonate, whetlier a solid or in solution, the 
anhydride is expelled with effervescence, and if a drop 
of lime-water, suspended on the end of a glass rod, is 
held in the tube just above the liquid, it is made turbid 
by the formation of insoluble calcic carbonate. 

Quantitative estimation. — Carbonic acid is usually 
estimated by the loss of weight suffered by the carbonate 
on treating it with a stronger acid, or by collecting and 
weighing the expelled anhydride itself. 

a. For the first method a convenient form of an ap- 
paratus is represented in the adjoining figure. 

The carbonate is weighed in the flask A and water is 
added. B is nearly filled with 



nitric acid ; G contains fused calcic 
chloride to absorb the moisture 
from the carbonic acid as it passes 
out, and so retain it in the appara- 
tus. The apparatus being put to- 
gether, with water enough in the 
flask ^-1 to cover the mouth of the 
tube leading from ^, close the 
mouth of the tube at e with the 
very small quantity of air out at 



(C^^?^ 




Fio-. 2. 



finger, and 
d ^ on lettin; 



suck a 
C air in 



80 § 60. BASES AND ACIDS WITH REAGENTS. 

again at d, the water will rise in the tube leading from 
A to J?, and, if the apparatus is tight, will remain at a 
stationary level above that of the water outside of the 
tube. Now, weigh the whole apparatus, apply suction at 
d to cause a little nitric acid to flow over into A from 
time to time, and in this manner keep up a slow evolution 
of carbonic acid; when all the carbonate is decomposed, 
and all the nitric acid transferred to the flask, apply a 
little heat to the latter ; then, by suction at c/, draw air 
through the apparatus as long as any acid taste is j^er- 
ceived in the gas, let the apparatus cool, and weigh it. 
The air should be caused to 2)ass through a calcic chloride 
tube before it goes into the apparatus, in order to dry it 
thoroughly. 

The loss of weight sufiered by the whole apparatus 
equals the carbonic anhydride, CO^. 

This method, otherwise very convenient, is, according 
to Prof S. W. Johnson, {American Journal of Science 
and Arts ^ Second y6'er/e5, 48, 111) liable to the objection, 
that in freeing the apparatus completely from carbonic 
acid, some vapor of water escapes the desiccating materi- 
al. He therefore proposes to fill the apparatus with car- 
bonic acid gas before weighing it, and then to weigh it 
again as soon as the decomposition of the carbonate is 
completed ; it is essential only, that the substance under 
examination dissolve freely in cold acid, and that the 
analysis and weighings be conducted in an apartment not 
liable to changes of temperature. 

His apparatus may be closely imitated by substituting 
for the acid reservoir in the above figure, another one 
consisting of a bulb of suflicient size bloWn on a tube of 
which one end, that passes just through the cork in the 
flask, has an internal diameter of 7 mm., is cut ofl" oblique- 
ly, and bent so that, on inclining the whole apparatus 
when put together, the acid can be made to flow from the 
bulb into the flask ; the other end of this tube is turned 



§ 60. CARBONIC ACID. 81 

upwards. Short pieces of thick-wallocl rubber tubing that 
Avill lit snugly on the outer termination of the calcic chlo- 
ride tube and the acid reservoir, at d and e, are slipped 
over them, and these rubber tubes are then provided with 
well-fitting stoppers of glass rod ; all tliesa joints must 
be air-tight. 

The carbonate is weighed as usual in the flask. A, bet- 
ter in the form of small fragments than of a powdei*, the 
acid reservoir is nearly filled with hydrochloric acid 
(Sp. Gr. = 1.1), the apparatus is put together, and, after 
the glass-rod stoppers are removed, it is connected with a 
generator of carbonic acid, and a rather rapid current of 
washed gas is passed through for about 15 minutes, or 
until the acid in the reservoir is saturated, and the air 
displaced in the flask ; then stop the opening at c?, discon- 
nect the apparatus from the generator, and close the open- 
ing at e, with care in this and all subsequent operations to 
handle the apparatus so as not to change its temperature. 

Weigh it immediately, loosen the stopper at d^ and in- 
cline the w^hole so that the acid wall flow over, little by 
little, and produce a slow decomposition of the carbonate. 
Close d again when the decomposition is ended, let the 
apparatus stand about 15 minutes, to be sure that it is 
cool, pass w^ell-dried carbonic acid gas in again for about 
a minute, in the same manner as at first, and finally w^eigh 
it after closing d and e. 

h. For the second method the following form of ap- 
paratus is highly recommended by Fresenius. 

In the apparatus represented by this figure e contains 
soda lime or caustic potash in 2:>ieces, a is a flask of about 
300 c.c. capacity, the arm / of the first U tube is filled 
wdth fused calcic chloride, and the arm/^ with pumice-stone 
that has been soaked in a concentrated solution of cupric 
sulphate, dried, and gently ignited so as to drive out the 
water of crystallization of the salt ; g contains pieces of 
glass, 6 to 10 drops of concentrated sulphuric acid in the 
4* 



82 



§ 60. BASES AND ACIDS WITH KEAGENTS. 



bottom and plugs of asbestos in the upper parts of both 
arms ; A is ' j^ filled with about 20 grms. of coarse grained 
soda lime, and the remaining ^ jg at h' is filled with coarse- 




Fii;-. 3. 

ly pulverized calcic chloride ; the arm h of the last U 
tube contains calcic chloride, and the arm h' soda lime. 

The carbonic acid evolved in a is deprived of its water 
and hydrochloric acid in ff' ; g enables the operator to 
observe the rapidity of the flow of the gas, while the acid 
is absorbed and weighed in g and 7ih' ; the contents of 
7<:¥ prevent carbonic acid and water from reaching the U 
tube, 7ih\ from the atmosphere. 

Weigh out the substance in a, add water, weigli g and 
hh' together, connect the various parts of the apparatus 
with each other, and the little funnel d with 5, and put a 
few drops of mercury in at d so as to close the tube at i. 

Pour the usual quantity of dilute nitric or hydrochloric 
acid in at d^ and, by suction at /, cause a little of the acid to 
flow over into the flask ; regulate the flow of the gas by 
slowly transferring fresh quantities of acid from h to a^ 
and applying a gentle heat to the contents of the flask. 

When the carbonate is completely decomposed, fill d 
several times with hot water and transfer the same to a / 
then, substitute the calcic chloride tube e for the funnel d, 



§ 61. PHOSPHORIC ACID. 83 

bring the contents of the flask to a gentle boiling, and 
continue the application of the heat until the bulb on f 
becomes hot ; draw about 1800 c.c. of air through the 
apparatus, by means of nn aspirator connected with /, 
then immediately separate a from /*, and weigh g and hh' 
again when they have become cold. The increase in 
weight gives the carbonic anhydride. 

The tube g can be used several times if it is carefully 
closed when not in use. If the tube hh' is used a second 
time, it will be safer to connect another with it on the 
outside, filled in the same way ; if this second tube does 
not gain in weight, the first one may be used a third time, 
with the same precaution ; if it does gain notably, use it 
alone in the third analysis, and re-fill hh' . 

c. It often hapi^ens that carbonic acid and chlorine are 
to be estimated in the same substance ; in this case, after 
making the determination of the acid by either of the 
above methods, using, of course, pure nitric acid to set it 
free, filter the contents of the flask if not perfectly clear, 
and precipitate the chlorine in the filtrate and washings 
with argentic nitrate. 

PHOSPHORIC ACID. H3PO4. 98. 

61 • All phosphates except those of the alkaline metals 
are insoluble in water, but all are soluble in acids. 

RcactionSo — When a solution of a phosphate is added 
to one of magnesia containing an ammoniacal salt and 
an excess of ammonia, a white flocculent precipitate, 
MgNH^PO^, is produced, which, after standing for a 
time in a warm place, becomes more granular and crys- 
talline ; in very dilute solutions the precipitate does not 
appear until after long standing, and is then crystalline, 
and adheres to the sides of the tube in the same manner 
as described under masrnesium. 



84 § 61. BASES AND ACIDS WITH REAGENTS. 

When a very small quantity of a solution of a phos- 
phate is added to a considerable quantity of a solution of 
amnionic molybdate, containing an excess of nitric acid, 
a lemon-yellow, pulverulent precij^itate is formed, at once 
or after long standing ; a portion of the ^precipitate ad- 
heres strongly to the sides of the tube. This precipitate 
is soluble in a solution of a j^hosphate and in ammonia, 
but is insoluble in dilute nitric acid in the presence of 
excess of the molybdate. The reaction is exceedingly 
delicate. 

Quantitative estimation. — a. In cases where the acid 
is free or combined with an alkaline metal only, the deter- 
mination of it may be made as magnesic phosphate, 
Mg,P,0, 

Neutralize a quantity of the solution of the substance 
containing not more than 0.2 grm. of the acid with am- 
monia, if it is acid, and add magnesia mixture (§ 18, h) 
as long as a precipitate is formed ; 12-15 c.c. of the re- 
agent will be required for 0.2 grm. of P^O^ ; then add 
diluted amnionic hydrate containing one part of ammonia- 
water of 0.96 Sp. Gr, and three of water, until the vol- 
ume of the mixture is about 110 c.c, and proceed farther 
as directed for the treatment of the same precipitate un- 
der magnesium (§50, a). It contains 63.96° |„ of phos- 
phoric anhydride, P20^. 

If in any case the precipitate has a somewhat suspi- 
cious flocculent appearance, and does not become crystal- 
line after long digestion, it had better be dissolved in 
dilute hydrochloric acid on the filter ; evaporate the solu- 
tion to dryness on the water-bath, treat the residue Avith 
dilute hydrochloric acid, and precipitate the phosphoric 
acid again with magnesia mixture as before. Neverthe- 
less it is best to avoid the necessity of this re-solution and 
re-precipitation if possible, by careful attention to the di- 
rections for removing silicic acid and other substances 
from the solution at the proper time and in the proper 



§ Gl. PHOSPiroRic ACID. 85 

place ; according to Kubel ( Versvchs Statione?i^ 10, 123) 
there is a loss of magnesia when the precipitated phos- 
phate is dissolved and re-precipitated. 

b. In the presence of alkaline earths, alnmina, ferric 
oxide, and manganous oxide, phosphoric acid is best de- 
termined indirectly, by precipitation as ammonic phospho- 
molyhdate. If silica is present, it must first be removed 
by evaporation to dryness in the usual manner (§ 58, a^ 1). 

To the solution, free from silicic acid, add the solution 
of ammonic molybdate containing an excess of nitric 
acid, whose preparation is described in § 3, /, and 
which, if made as there directed, contains 5°|„ of molyb- 
dic acid, in such a quantity that the amount of molybdic 
acid added shall be from 40 to 60 times as great as that 
of the phosphoric acid supposed to be in the solution ; 
since the molybdic acid must be so largely in excess, it is 
well to take a quantity of the solution of phosphate that 
contains not over 0.1 grm. of the acid, and the solution 
should be tolerably concentrated. Digest the mixture 
from 12 to 2-4 hours at a temperature of about 40° C. ; then 
take out a small sample of the clear liquid with a pipette, 
mix it in a test-tube with its volume of ammonic molyb- 
date, and heat the mixture gently for an hour or more. 
If more of the precipitate appears, rinse the test-tube into 
the beaker again, add more ammonic molybdate, digest 
12 hours longer, and repeat the test. Not until the mix- 
ture remains perfectly clear in this test may the precipita- 
tion be considered as finished. 

Collect the precipitate on a small filter, rinse the beaker 
out with portions of the filtrate, and wash the contents 
of the filter with a mixture of 100 parts of the solution of 
ammonic molybdate, 20 parts of nitric acid (Sp. Gr. = 1.2), 
and 80 parts of water {l^Yes, Zeitschrift G, 405), until, in 
case lime was present, the filtrate gives no turbidity in 
strong alcohol to which sulj^huric acid has been added. 
Dissolve the precipitate in the smallest quantity of am- 



86 61. BASES AXD ACIDS WITH REAGEJ^^TS. 

monia (Sp. Gr. = 0.96), wash out tlie filter with a mix- 
ture of 3 parts of water and 1 of ammonia, and wash off 
what remahis adhering to the Avails of the beaker, in 
which the phospho-molybdate was precipitated, with a 
little of the same ammonia water, or else collect this so- 
lution of the whole precipitate in that beaker ; add di- 
lute hydrochloric acid to the strong ammoniacal solution, 
until the yellow precipitate, that appears with each drop 
of the acid added, begins to dissolve again with some dil- 
ficulty, showing that the ammonia is nearly neutralized, 
then add the magnesia mixture as long as a precipitate is 
produced, and the proper amount of the diluted ammonia, 
and proceed as in a. 

Latschinow {Fres. Zeltschrift 7, 215) asserts that this 
precipitate of ammonio-magnesic phosphate must be fused 
with potassic sodic carbonate, the fused mass extracted 
with water, and this solution precipitated again with the 
magnesia mixture in the usual manner, after addition of a 
little citric acid. 

c. In the absence of at least all but small quantities of 
iron and aluminium, phosphoric acid may be determined 
with sufficient accuracy for industrial purposes by a volu- 
metric method that depends upon the following reactions. 
First, w^hen a solution of uranic salt is added to one of a 
phosphate containing no other free acid than acetic, the 
uranic oxide is immediately precipitated in combination 
Y/ith phosphoric acid. Second, a solution containing the 
least traces of uranic oxide gives a brown precipitate with 
potassic ferrocyanide. 

Preparation of the standard solutions. 

1. Dissolve 12.6056 grms. of pure crystallized hydric 
disodic phosphate, that does not show the least signs of 
efflorescence, and has been thoroughly dried in powder 
by pressure between folds of bibulous paper, in about 300 
c.c. of v\^ater, and, when the temperature of the solution 
is 15° C, make the volume up to exactly 500 c.c. with dis- 



61. PHOSPHORIC ACID. 87 

tilled water. One cubic centimetre of such a solution con- 
tains 0.005 grni. of pliosplioric anhydride, P„0^. 

2. Dissolve 100 grms. of sodic acetate in 900 c.c. of 
water, and add 100 c.c. of concentrated acetic acid. 

3. Dissolve about 33 grms. of uranic acetate in about 
1 litre of water, and j^roceed to titrate this solution with 
reference to the standard solution of phosphate so that 1 
cubic centimetre of it shall exactly precipitate 0.005 grm. 
of phosphoric anhydride, as follows. 

Put 25 c.c. of the standard phosphatic solution in a 
small flask, add 5 c.c. of the solution of sodic acetate, 
heat to about 50° C, add 5 or 10 c.c. of the uranic solution 
from a burette or graduated i^ipette, heat to boiling, and 
let the mixture stand a few minutes ; the precipitate will 
settle quickly, and a drop of the clear supernatant liquid 
can be taken out on the end of a small glass rod, and 
tested with the solution of potassic ferrocyanide for ex- 
cess of uranic oxide ; this test is best made by letting the 
drop fall gently in the middle of a small shallow pool of 
the solution of ferrocyanide, on a white porcelain plate, 
when the slightest excess of the uranic oxide in the solu- 
tion w'ill be manifested by the formation of a brown zone 
where the two liquids come in contact ; the color soon 
spreads throughout the entire liquid. If no color appears, 
add 5 c.c. more of the uranic solution, boil again, let set- 
tle, and test a droj) of the supernatant liquid in another 
little pool of the ferrocyanide, and so proceed until a 
brown color is produced in the test drop. Suppose that 
this brown color was obtained after adding 20 c.c. of the 
uranic solution, but not after adding 15 ; repeat the trial 
now with a fresh quantity of the standard phosphatic so- 
lution, adding 16 c.c. of the uranic solution at once, be- 
fore making the test, and repeating the test after each 
addition of a cubic centimetre at a time. If, in this trial, 
we find that a brown color is obtained with 17 c.c. but 
not with 16, we may make a third trial with another por- 



88 62. BASES AND ACIDS WITH REAGENTS. 

tion of the standard pbosphatic solution, and locate the 
point of saturation more accurately between 16 and 17 
cubic centimetres, beginning with 16.1 c.c. and so on. 

If we find, finally, that 25 c.c. of the standard phos- 
phatic solution requires 16.5 c.c. of the uranic solution for 
the complete precipitation of the phosphoric acid, then, 
evidently, to every 16.5 c.c. of the former, 8.5 c.c. of pure 
water must be added, in order to make a standard uranic 
solution, each cubic centimetre of which shall be exactly 
equivalent to 0.005 grm. of phosphoric anhydride. 

The respective quantities of uranic solution and water 
being carefully measured out and mixed, for making half 
a litre or a litre of the standard solution, this solution 
should be tested, in order to be sure of its value with 
respect to phosphoric acid. Dilute 5 c.c. of the standarT 
j^hosphatic solution, add 1-2 c.c. of sodic acetate, and 
then add the uranic solution from a burette graduated into 
^ Ijq cubic centimetres ; exactly 5 c.c, not a tenth more or 
less, should be required before the reaction with the ferro- 
cyanide is given. 

The method of determining phosphoric acid volumet- 
rically, with the aid of this standard uranic solution, is 
the same as that just described for the determination of 
the strength of this solution as originally prepared. The 
amount of phosphoric anhydride in the quantity of the 
solution taken is then given, by the product of 0.005 
into the number of cubic centimetres of standard uranic 
solution required to precipitate the acid. 

NITRIC ACID. IINO3. 63. 

62 • All nitrates are soluble in water. 

Reactions. — If a nitrate is heated with concentrated 
sulphuric acid and copper turnings, red fumes of nitric 
peroxide, NO^, become visible in the upper part of the 



62. NITKIC ACID. 89 

tube, particularly if it is held over white paper and looked 
through lengthwise. 

If a nitrate is mixed in a test-tube with strong sul- 
phuric acid and the mixture is allowed to cool, and a con- 
centrated solution of ammonio-ferrous sulphate is then 
poured slowly down the sides of the tube so as to float 
on the surface of the liquid in it, a colored ring is formed, 
the tint of Avhicli may range from a rose color to a dark 
brown, according as little or much nitric acid is present. 

If a solution of a nitrate is poured into a test-tube con- 
taininof 2-3 orrms. of a mixture of clean iron filino^s and 
granulated zinc, or of sodium amalgam, and 5-6 c.c. of a 
strong solution of potash or soda are added, and the mix- 
ture is heated to boiling, ammonia is set free ; its presence 
in the tube may be detected by moistened turmeric-paper, 
or by holding in the tube a drop of Nessler's solution, 
suspended on the end of a glass rod ; this solution will be 
colored reddish-brown. 

A delicate test for nitric acid in rain-water consists in 
acidifying 100 c.c. of the water with 2 or 3 drops of con- 
centrated sulphuric acid, adding 2 or 3 pieces of pure 
zinc, and, immediately, a freshly prepared mixture of 
2)otassic iodide Avith a little boiled starch paste ; the pres- 
ence of nitric acid is indicated by a blue color. The re- 
agents used should be tested by mixing them together 
without the water. 

If the water contained nitrous acid, it will give a blue 
color with potassic iodide and starch paste alone. 

Qliaatitativef estimation.— a. Of the numerous meth- 
ods of determining nitric acid, that of Schlossing has 
proved the most satisfactory in all cases. Friihling and 
Grouven have simplified Schlossing's apparatus somewhat. 
{Die landwirtJiscliaftlichen 'Versucks-Stationen, 9, 13.) 

The dissolved nitrate is introduced into the flask A, of 
about 400 c.c. capacity, whose mouth can be perfectly 
closed by a rubber cork, through which passes a glass 



90 



62. BASES AND ACIDS WITH REAGENTS. 



tube, a / the rubber tube he should be about 8 cm. long, 
and have a clam^) on it ; d is another narrow caoutchouc 
tube, 15 cm. long. The neck of the jar B is ground on 
the outside so that a. rubber tube slipped over it will 
more readily make a tight joint ; a small glass tube, </, 
is connected with the jar by the stop-cock li and rubber 
tubing ; another glass tube, ?, bent at an obtuse angle, and 
reaching above the level of the stop-cock yL', is fastened in 
the tubulure m of the jar by a good cork. This last- 
mentioned tube being in place, open the stop-cock h^ pour 

a little boiled 
c iT ^ yi.^ water into the jar 

til rough the tube 
7, and then j^our 
in mercury until 
it rises to the 
lower rim of the 
rubber tube f on 
the neck of the 
jar; close the 
stop-cock, put the 
jar in the mercury 
trough so that 
the mercury rises 
above the tubulure, and remove the glass tube I and 
the cork ; now, by means of a pipette, the lower end of 
which is bent so that it can be inserted in the tubulure, 
introduce 50 c.c. of well-boiled milk of hme, and then 
cover the mercury in the trough with watea* to the depth 
of about 3 cm. 

The solution of the nitrate in A, which must be neutral 
or alkaline, is boiled down to a small volume, while the 
open end of d is immersed in water ; when the bubbles of 
gas escaping from A are completely condensed in passing 
through the water, showing that all the air has been ex- 
pelled from the liquid in A, close the clamp on hc^ and 




§ 62. NITKIC ACID. 91 

dip d in a glass containing a solution of ferrous chloride 
in hydroclilorij acid, remove the lamp from A, and open 
the clamp just enough to allow this solution to flow into 
the flask rather rapidly ; when about 200 c.c. of the fer- 
rous solution have passed in, replace this solution by dilute 
hydrochloric acid, and allow three or four j^ortions of this 
to flow in also, and thus wash all the ferrous salt out of the 
tube ; finally rinse the tube into the flask with a little dis- 
tilled water. Now, close the clamp on hc^ and, without 
allowing any air to enter the tube, insert d m the tubulure 
of the jar B, re2:)lace the lamp under A, immediately open 
the clamp on 5c, while holding the rubber tube tightly 
compressed between the fingers until a pressure is felt 
from within ; then remove the fingers and allow the nitric 
oxide gas that is generated in the flask to pass into the 
receiver B. The reaction is generally terminated in about 
8 minutes ; so long as nitric oxide is escaping it bubbles 
up through the milk of lime in B, but as soon as nothing 
but water and hydrochloric acid pass over, both are 
absorbed by the milk of lime, and the bubbling of the gas 
through it ceases. 

If the receiver B is filled with gas before all the nitric 
acid in A is decomposed, close the clamp on hc^ remove 
the lamp immediately from under A, take the rubber tube 
d out of the tubulure and let it lie in the water over the 
mercury, while the receiver is emptied in the manner de- 
scribed below ; then fill the receiver again with mercury 
and milk of lime as directed above, insert d in the tubu- 
lure again, apply heat to A while the tube he is closed 
with the fingers only, and proceed as before, until the de- 
composition of the nitric acid is finished. 

When the evolution of gas finally ceases, close 5c, re- 
move d from the tubulure, and proceed to empty the gas 
from B. To this end, mount another flask, C, in the same 
manner as A was arranged, put about 100 c.c. of distilled 
water in it, attach a rubber tube about 12 cm. long to the 



92 62. BASES AND ACIDS WITH RKAGENTS. 

glass tube that passes through the well-fitting rubber cork 
in the mouth of the flask, and j^ut a clamp, y, on the end 
of the tube. Fasten this clamp open and boil the water 
in C until the air is completely expelled from the flask, 
and, while steam is still escaping from the end of the rub- 
ber tube, slip it over the glass tube cj on the receiver, and 
at the same moment open the stop-cock h y the aqueous 
vapor, from the water that continues to boil in the flask, 
condenses at first in the neck of the receiver and washes 
the milk of lime out of the upper part of it and out of 
the glass tube ; if any milk of lime is carried into C in 
the operation that follows, the analysis is w^orthless. 

Now, remove the lamp from C, and a current starts iw 
the opposite direction, Avhich carries the nitric oxide into 
C ; the rapidity of the flow can be regulated by compress- 
ing the rubber tube between the fingers ; as soon as the 
milk of lime in the receiver has reached the rim of the 
rubber tube /, close the stop-cock h and conduct 20 or 30 
c.c. of pure hydrogen into the receiver, open the stop-cock 
and allow tins gas to flow into C ; rej^eat this two or three 
times, thus carrying the last traces of nitric oxide from 
B to C. Now, close h again and also the clamp y near 
this end of the tube, connect the rubber tube Avith a 
small gasometer containing oxygen, open the cock of the 
gasometer and the clamp y again, and oxygen will j^ass 
into C and convert the nitric oxide into nitric acid ; when 
all the oxygen has passed into the flask that will, close 
the gasometer cock, disconnect the rubber tube from it, 
and, after about 15 minutes, determine the nitric acid in 
the liquid in C by means of the '1^^ standard solution of 
soda ; each cubic centimetre of the sodic solution, con- 
taining '1^^ of an equivalent of sodic oxide (Na^O), will 
combine with 'j^^ of an equivalent of nitric anhydride 
N^^^, expressed in milligrammes = 5.4 mgr. or 0.0054 grm. 

h. Nitric acid may be very conveniently estimated in 
nitrates, as, for example, when it is desired to test the 



§ 62. NITEIC ACID. 93 

purity of nitre or of Chili saltpetre, by its expulsion at a 
high temperature by another acid, as silicic or chromic, 
that is not volatile at such a temperature. 

Fuse a quantity of the salt, free from carbonic acid, 
amnionic salts, or organic matter, at the lowest possible 
temperature, j^our it on a warm porcelain plate, pulverize 
the cake, and dry the powder thoroughly; then put 2-3 
grms. of finely powdered quartz in a platinum crucible, 
and ignite it strongly; add to this about 0.5 grm., care- 
fully weighed, of the nitrate prepared as above directed, 
mix the two substances carefully with a dry glass rod, 
wipe off the rod with a little more of the quartz powder, 
and weigh the whole; ignite the well-covered crucible 
with its contents, for half an hour, at a barely visible red 
heat, weigh, and count the loss as nitric anhydride. Sul- 
phates or chlorides are not decomposed under these cir- 
cumstances, but, if carbonates are present, they must be 
removed by previous treatment of the salt with hydro- 
chloric acid in slightest possible excess, and evaporation 
to dryness on the water-bath. 

c. A very convenient method for determining nitric 
acid in nitrates is given by C. Noellner. {Fres. Zeitschrift 
6, 375). It depends upon the solubility of amnionic nitrate 
in absolute alcohol, and the insolubility of other salts of 
the alkalies and alkaline earths. 

Heat a quantity of the salt containing not more than 
0.2 grm, of the nitre with a small quantity of a solution of 
aramonic sulphate ; ammonic nitrate is formed, and this 
remains in solution while all other salts are ^precipitated, 
when absolute alcohol is added to the liquid ; let the mix- 
ture stand a few minutes, filter it, wash the precipitate, 
add an alcoholic solution of potassa to the filtrate, collect 
the precipitated potassic nitrate on a dried and weighed 
filter, wash it with alcohol, dry it at 100°, and weigh it. 



94 63. BASES AND ACIDS WITH REAGENTS. 

HYDROCHLORIC ACID. HCl. 36.5. 

63. Chlorides of all the metals in the list in § 43 are 
soluble in water. Plumbic chloride is sparingly soluble 
in cold water but readily soluble in hot. 

Reaction. — When argentic nitrate is added to a solu- 
tion containing a chloride or hydrochloric acid, a white 
precipitate is produced, AgCl, which, if at all abundant, 
is collected together in curdy flakes on violently agitating 
the mixture. This precipitate is blackened on exposure 
to the light, is insoluble in dilute nitric acid, but is solu- 
ble in ammonia ; from this solution it is re-precipitated 
unchanged, on addition of nitric acid in excess. It can 
be fused without decomjDOsition. In contact with metal- 
lic zinc in the presence of sulphuric acid, it is decomposed, 
metallic silver being set free. 

Quantitative estimation. — Hydrochloric acid or chlo- 
rine is most easily and accurately determined by pi-ecipi- 
tation as argentic chloride, and the estimation may be 
made either by a gravimetric or a volumetric process. 

a. Grai'hnetric Process. — Add the solution of argentic 
nitrate, containing a slight excess of nitric acid, to the so- 
lution of the chloride, heat the mixture and stir or shake 
it vigorously to cause the precipitate to settle more read- 
ily, let it stand until the supernatant liquid is quite clear, 
decant the liquid through a small filter, agitate the pre- 
cipitate with hot water, transfer it to the filter with the 
aid of a little water acidulated with nitric acid, wash it 
at first with the same acidulated water and afterwards 
with pure water, until the washings give no turbidity 
with amnionic chloride. 

Dry the filter and its contents, separate the latter from 
the filter as completely as j^ossible, burn the filter on the 
crucible cover, add the ash to the precipitate in the cruci- 
ble, heat the whole some time with a little nitric acid, add 
a little liydrochloric, evaporate carefully to dryness on the 



63. HYDEOCIILOEIC ACID. 95 

water-bath, ignite the residue until it begins to fuse, and 
weigh it. 

When this precipitate of argentic chloride is produced 
in the presence of much organic matter, it, together with 
the ash of the filter, must be fused with 3 or 4 parts of 
pure sodic carbonate, and the fused mass exhausted with 
water, the insoluble residue well washed, and the solu- 
tions and washings re-precipitated with argentic nitrate, 
and the precipitate treated as directed above for washing 
and ignition. 

The precijiitate contains 24.74" |y of chlorine. 

h. Yohtmetric Process. — To prepare the standard solu- 
tion of argentic nitrate, dissolve 18.75-18.8 grms. of 
the pure fused salt in 1100 c.c. of distilled water, filter 
the solution if necessary, and mix all parts of it well 
together. 

Weigh out accurately four portions of pure sodic chloride 
of 0.1-0.18 grms. each; the salt should have been pre- 
viously gently ignited, pulverized while warm, and kept 
in a w^ell stoppered bottle until wanted for use. 

Dissolve each portion of the salt in 20-30 c.c. of 
water, and add 2 or 3 drojDS of a cold saturated solution 
of potassic chromate. Now, allow the solution of argen- 
tic nitrate to flow from a burette, graduated into ^1^^ c.c, 
into one of these solutions, slowly and with constant stir- 
ring ; each drop as it comes in contact with the liquid 
23roduces a red precipitate, which, at first, disappears when 
mixed with tlie rest of the solution, but finally the addi- 
tion of a single drop causes the red color to remain j^er- 
manent ; all the chlorine has united with the silver. 

A solution of argentic nitrate is to be made, one litre 
of which will exactly precipitate the chlorine in ^Ij^of 
an equivalent of sodic chloride expressed in grammes, or 
5.85 grms. If the amount of sodic chloride in the solu- 
tion tested in this first experiment was 0.11 grm., and 



96 63. BASES AND ACIDS AVITII REAGENTS. 

18.7 c.c. of argentic nitrate were required, Ave learn by 
the proportion, 

0.11 : 18.7 = 5.85 : 994.5, 

how much of the argentic solution that we liave made 
would be required for the desired purpose ; we must 
therefore add 5.5 c.c. of distilled water to 994.5 c.c. of the 
argentic solution, to make a litre of a solution that shall 
be exactly equivalent to 5.85 grms. of sodic chloride, or 
3.55 grms. of chlorine ; or, since it is more convenient to 
measure out one litre of the solution, and add a small 
quantity of water accurately measured with the pipette, 
we may learn from the proportion, 

994.5 : 4.5 = 1000 : x, 
how much w^ater will be required for one litre. 

Repeat the test made with one portion of the salt with 
two of the remaining three portions, keeping the first at 
hand as a standard of comparison, substitute the mean of 
the quantities of salt taken and of the three corresj^ond- 
ing results in the place of the first and second terms in 
the first proportion given above, and make the standard 
silver solution accordingly ; then, in order to be sure that 
the work has been correctly done, rinse the burette out 
with a little of the solution last prepared, fill u^^ to the 
zero mark with this solution, and make a fourth trial with 
the last w^eighed portion of the sodic chloride. The num- 
ber of cubic centimetres of the standard solution required, 
multiplied by 0.00585, should give a product exactly equal 
to the amount of salt taken. 

One cubic centimetre of this solution corresponds to 
0.00355 grm. of chlorine. 

The solution in which chlorine is to be determined 
with the aid of this standard solution must not be acid 
in the slightest degree, but should be neutral, or at the 
most very slightly alkaline. If strongly alkaline, it should 
first be neutralized with nitric acid ; if acid, with sodic 



§ 64. HYDROCYANIC ACID. 97 

carbonate. Of course, neither of these reagents should 
contain any chlorine. Greater accuracy is secured, more- 
over, by using the same volume of a solution containing 
about the same amount of clilorine as in determining the 
standard of the argentic solution in the beginning — that 
is, about 25 c.c. containing about 0.15 grm. of chlorine. 

It is well, also, to have on hand an accurately titrated 
solution of sodic chloride, containing exactly 5.85 grms. 
of sodic chloride in the litre, and which, therefore, is ex- 
actly equivalent, cubic centimetre for cubic centimetre, to 
the argentic solution. Then, if it is feared in any case 
that too much argentic nitrate has been added, a cubic 
centimetre of this solution can be put in, when the red 
coloration will disappear, and argentic nitrate can be add- 
ed again more cautiously ; finally, when the desired result 
is obtained, subtract one from the number of cubic centi- 
metres of argentic solution used. 

UYDROCTANIC ACID HCy. 

64. Cyanides of manganese, zinc, and copper, are in- 
soluble in water. 

Reactions. — Cyanides give a Avhite precipitate, AgCy, 
with argentic nitrate, insoluble in dilute nitric acid, and 
somewhat difficultly soluble in ammonia ; when heated, 
it is decomposed, metallic silver being left behind. 

If a cyanide is treated with dilute sulphuric acid in a 
watch-glass, and another watch-glass, with a drop of 
lammonic sulphide charged with excess of sulphur in its 
'centre, is quickly inverted over the first glass, the hydro- 
cyanic acid evolved from the cyanide is absorbed by the 
ammonic sulphide, and on evaporating the drop in the 
upper glass to dryness at a very gentle heat, ammonic 
sulphocyanate is left, which, if moistened with a drop of 
ferric chloride, gives a deep red color. 
5 



98 65. BASES AND ACIDS WTTU EEAGENTS. 

HTDROFERPvOCYANIC ACID. HCfy. 

65« Ferro cyanides of iron, zinc, manganese, lead, and 
copper, are insoluble in water ; ferrocyanides of iron and 
copper are insoluble in dilute acids. 

Reactions* — Ferrocyanides give a deep blue precipitate 
of Prussian blue, FCjFe^Cyjg, with ferric chloride, which 
is not soluble in dilute hydrochloric acid, but is decom- 
posed by sodic hydrate, the blue color being changed to 
red. 

HYDROSULPHURIC ACID. H^S. 

66. Sulphurets of arsenic, lead, copper, iron, manga- 
nese, and zinc, are insoluble in water ; the first three are 
insoluble in dilute acids. 

Reactions. — Sulphurets give with argentic nitrate a 
black precipitate, Ag^S, insoluble in dilute nitric acid and 
in ammonia. 

When sulphurets are treated with hydrochloric or sul- 
phuric acid, sulj3huretted hydrogen, H^S, is cA^olved Avith 
effervescence ; the gas may be recognized by its disagree- 
able odor, and the property of blackening lead-paper. 

HYDRIODIC ACID. HI. 

67. Plumbic iodide is sparingly soluble in cold water, 
but readily soluble in hot ; other iodides are soluble. 

Reactions. — Iodides give a yellow j^recipitate, Agl, 
with argentic nitrate, which is very sj^aringly soluble in 
ammonia and in dilute nitric acid. 

If enough potassic dichromate is added to a solution 
of an iodide to give it a pale yellow color, and tlien a lit- 
tle hydrochloric acid, iodine is set free, which, if it is 
present in notable quantity^ gives the solution a darker 



§ 68. HYDROFLUORIC ACID. § 69. OXALIC ACID. 99 

color ; a drop of this solution on starch paper colors it 
blue ; the latter reaction is very delicate. 

HYDROFLUORIC ACID. HF. 

68. Calcic and magnesic fluorides are difficulty soluble 
in water and acids. 

Reactions. — When a fluoride in powder is moistened 
with concentrated sulphuric acid, in a leaden or platinum 
cup, and gently heated, hydrofluoric acid is evolved ; if 
the cup is covered with a piece of Bohemian glass that is 
protected with a coating of wax, except along a few lines 
where the wax has been removed with a sharp point, the 
glass will be corroded on these lines, in a few hours at 
the most. If but a small quantity of hydrofluoric acid is 
present, the marks may not be seen until all the wax is 
carefully cleaned ofl* and the glass is breathed upon. 

To be sure that these faint marks are i^roduced by 
traces of hydrofluoric acid in the substance, wipe the 
glass off carefully with water, and see that they can be 
developed again by the breath — and be sure, also, that the 
sulphuric acid used does not contain traces of hydroflu- 
oric acid, as it sometimes does. 

If a silicate is present, this reaction may not take place ; 
in this case mix the substance with strong sulphuric acid 
in a watch-glass, heat until the mass is dry, and wash the 
residue off with water. If fluorine was present, the glass 
will be found to be corroded where it came in contact 
with the substance. 

OXALIC ACID. H2C2O4. 90. 

69. Oxalates of barium, calcium, magnesium, iron, 
manganese, zinc, lead, and coj^per, are sparingly soluble, 
or insoluble, in water, but soluble in dilute acid. 

Reactions. — Oxalates are decomposed, but not black- 
ened when heated. 



100 § 69. BASES AISD ACIDS AVITH REAGENTS. 

When an oxalate is heated with plumbic binoxide and 
concentrated sulphuric acid, a brisk effervescence ensues, 
carbonic acid being set free ; if a drop of lime-water, on 
the end of a glass rod, is held in the tube above the 
liquid, it is made turbid by precipitation of calcic car- 
bonate. 

A solution of an oxalate in which no free acid except 
acetic is present, gives a fine white precipitate, CaC^O^, 
with calcic sulphate, insoluble in acetic acid, 

Quantitative estimation. — a. Oxalic acid may be ac- 
curately determined by a volumetric process with potassic 
permanganate. 

First make a ^|j„ standard solution of oxalic acid, by 
mixing together 10 c.c. of the standard acid already 
made and 90 c.c. of distilled water. Put 50 c.c. of this 
new standard solution, containing 0.315 grm. of the acid, 
in a beaker, add about 100 c.c. of water and 6 to 8 c.c. of 
concentrated sulphuric acid, and heat to about 60° C. ; 
put the beaker on a sheet of white paper and add the 
standard solution of permanganate with constant stirring, 
in the same manner as directed for the determination of 
iron (§ 52). When the reaction is completed, make another 
trial with the other 50 c.c. of the ^|j„ standard acid. 

The standard of the permanganic solution with refer- 
ence to oxalic acid being determined, to estimate the acid 
in any substance, whether free or combined, the substance 
must be freed from all other compounds that act in the 
same manner on the permanganate, such as ferrous oxide, 
or organic matter ; dissolve it in water or hydrochloric 
or sulphuric acid, add 400 to 500 c.c. of water for every 
gramme of oxalic acid supposed to be present, and 6 to 8 
c.c. of concentrated sulpliuric acid, and proceed to titrate 
with the permanganic solution in the usual way. Let 
m = the amount of permanganate used to oxidize 0.315 
grm. of crystallized oxalic acid, or 0.18 grm. of oxalic an- 
hydride, and m' the amount required to oxidize the acid 



§ 70. ACETIC ACID. 101 

in the quantity of substance taken. Then from the pro- 
l^ortlon, 

m : 0.18 = m' : X, 
we may learn how much oxalic anhydride, C^Og, was con- 
tained in the substance analyzed. 

h. Oxalic acid may be estimated in any substance con- 
taining it and free from carbonic acid, by converting it 
into carbonic acid with the aid of manganic oxide and 
concentrated sulphuric acid, and determining this car- 
bonic acid. Weigh the substance in the flask A, Fig. 1, 
§ 60, add about the same weight of manganic oxide free 
from carbonic acid, fill B with concentrated sulphuric 
acid, weigh the whole apparatus, and proceed further as 
in the estimation of carbonic acid with this form of ap- 
paratus (§ 60, rt). Each equivalent of oxalic anhydride, 
C^Og, yields two equivalents of carbonic anhydride, CO^. 

ACETIC ACID. HC2H3O0. 60. 

70. All acetates are soluble in water. 

Reactions. — Acetates are blackened when quickly heat- 
ed to a high temperature, carbon being set free. 

If a neutral acetate is mixed Avith a solution of ferric 
chloride, a deep red liquid is produced ; on boiling the 
mixture a red precipitate is formed. 

If an acetate is heated with concentrated sulphuric acid 
and alcohol in about equal volumes, acetic ether is disen- 
gaged, the pleasant aromatic odor of which is best distin- 
guished from that of common ether, which may be 
formed from sulj^huric acid and alcohol alone, after the 
liquid has become quite cold. 

Quantitative estimation. — Free acetic acid may be es- 
timated by a volumetric process', with the aid of the 
standard sodic solution. 

Since neutral sodic acetate has a slightly alkaline re- 
action, it is best to ascertain first, the relation between 



102 § T"!. BASES AXD ACIDS WITH REAGENTS. 

this standard solution and one of acetic acid of known 
strength. For this purpose add a measured quantity of 
the standard sulphuric acid to a solution of sodic acetate, 
but not enough to decompose the whole of the acetate. 
Each cubic centimetre of the sulphuric acid, containing 
0.04 grm., will set free an equivalent quantity of acetic 
anhydride, = 0.051 grm., or of the hydrated acid, 0.06 grm. 

Knowing, then, how much acid has been set free, we can 
titrate the mixture with the standard sodic solution, and 
learn how much acetic acid each cubic centimetre of the 
sodic solution will neutralize. 

Merz recommends the use of a tincture of turmeric as 
a coloring matter that is not aiFected by neutral sodic ace- 
tate ; the addition of a single drop of the soda solution to 
a solution of sodic acetate colored yellow by this tincture 
produces a brown color, while a drop of acetic acid re- 
stores the yellow color. ( Wagner's Jahresbericht^ 13, 498.) 



TARTARIC ACID. IIsCJI.O,. 150. 

71. Tartrates of barium, calcium, zinc, and copper, are 
difficultly soluble in water. 

Reactions. — When tartrates are heated, they are black- 
ened, and an odor of burnt sugar is given off. 

If a solution of free tartaric acid, that is not too dilute, 
is mixed with a solution of potassic acetate, a crystalline 
precipitate, KHC^H^Og, is formed at once, or after some 
time, or after violent agitation, or addition of an equal 
volume of alcohol. If the two solutions are very concen- 
trated, and are stirred in a watch-glass, a deposition of 
crystals marks the track of the rod over the glass. 

Calcic chloride gives a white precipitate, CaC^H^Og, in 
solutions of a neutral tartrate, the fonnation of which is 
hastened by violent agitation ; the presence of amnionic 
chloride only retards the appearance of the precipitate, 



§ 7:2. CITRIC ACID. 103 

but does not prevent it. The precipitate is soluble in 
boiling sodic hydrate, but re-precipitation follows on 
cooling. 

With lime-water in large excess, so as to turn red lit- 
mus-paper blue, tartaric acid gives the same white precipi- 
tate. 

With calcic sulphate, tartaric acid in tartrates gives no 
precipitate, thus distinguishing it from oxalic acid. 

With argentic nitrate, neutral tartrates give a precipi- 
tate that is turned black w^hen the mixture is boiled. 

Quantitative estimation.— An approximate determina- 
tion of tartaric acid may be made by adding potassic 
acetate to its moderately concentrated solution, and con- 
siderable alcohol, collecting the precipitate on a weighed 
filter, washing it with alcohol, and drying it at 100° C, 
and weighing. 

The residue of potassic tartrate, KHC,H,0,, contains 
70.18*1, of tartaric anhydride, C,H,0,. 

CITRIC ACID. H3C6H5O7. 

72. Citrates of barium, calcium, and aluminium, are 
sparingly soluble in water. 

Reactions.— When citric acid is heated, it fuses at first, 
and then carbon is separated with the evolution of pun- 
gent acid fumes. Citrates are blackened when heated. 

Citrates give no precipitate with potassic salts. 

With lime-water in excess, at ordinary temperatures, 
they give a very slight precipitate, which, on boiling, be- 
comes quite abundant, but is mostly dissolved when the 
mixture is cooled. 

Calcic chloride gives a precipitate Ca3(C,H,0,)„ m 
solutions of neutral citrates, which, if obtained without 
heat, is soluble in aramonic chloride ; it is re-precipitated 
from this solution on boiling, and is not then soluble in 
ammonic chloride ; it is insoluble in potassic hydrate. 



104 § 73. BASES AND ACIDS WITH REAGENTS. 

MALIC ACID. II2C4H4O5. 134. 

73i Malate of lead is difficultly soluble in water 

Reactions. — When malic acid is heated, it froths, ]3un- 
gent acid vapors being set free, and crystals of maleic and 
fumaric acids are condensed in the colder parts of the 
tube. 

Malates give no 2:)recipitate with potassic salts, nor 
with calcic hydrate or sulphate, even on boiling. 

With calcic chloride no i^recipitate is formed unless the 
solution is concentrated and the mixture is boiled ; if this 
precipitate, CsiCJIfi,,2Ilfi, is dissolved in a very little 
hydrochloric acid, ammonia added, and the mixture boiled, 
the calcic malate is re-precipitated ; but if it is dissolved 
in considerable acid, no precipitate is formed on adding 
ammonia and boiling ; alcohol will 2)recipitate the salt 
from this solution. 

Quantitative estimation. — An approximate determina- 
tion of malic acid may be made by adding calcic hydrate 
in excess to its highly concentrated solution, free from 
citric, tartaric, or sulphuric acid, and then adding consid- 
erable alcohol, collecting the j^recipitate on a dried and 
weighed filter, washing with alcohol, drying at 100° C, 
and weighing. 

The residue contains 67. 44°!^ of malic anhydride, 

LACTIC ACID. IIC3H5O3. 90. 

74. All lactates are soluble in water ; only zincic lactate 
is somewhat difficultly soluble in cold water. 

Reactions. — Lactates are blackened when heated. 

If a liquid containing free lactic acid is boiled with zin- 
cic oxide or carbonate, the filtered solution will dej^osit a 
crystalline crust on its surface, or acicular crystals, on 
cooling. 



§ 75. UKIC ACID. 105 

Quantitatiye estimation. — This acid in the free state 
may be determined by a volumetric process, the same as 
for the determination of acetic acid. The solution, free 
from acetic or other free acid except lactic acid, is titrated 
with the standard sodic solution. Each cubic centimetre 
of sodic solution required corresponds to 0.81 grm. of the 
anhydrous acid, CgH^^jO^. 

To remove acetic acid as well as carbonic from the so- 
lution, before estimating the lactic acid, evaporate a por- 
tion of the liquid in the water-bath with the addition of 
pure quartz sand and with constant stirring towards the 
end of the operation ; continue to heat the dry residue 
until no more acid odor is given oif, then treat it with 
water, filter, and wash the sand on the filter as long as the 
washings are acid, and determine lactic acid in the filtrate 
with the standard sodic solution as above. 

URIC ACID. H2C5H2N4O2 + 4aq. 804. 

75. This acid is but slightly soluble in water, and is 
insoluble in alcohol. Alkaline urates are soluble in water ; 
others are insoluble. 

Reactions. — If uric acid or a urate is heated with mod- 
erately strong nitric acid, the mixture filtered if not clear, 
the filtrate carefully evaporated to dryness, and the resi- 
due moistened with ammonia, a beautiful purple color 
(murexide) appears. 

In urinary sediments, uric acid may often be recognized 
under the microscope by tlie rhombic six-sided plates, or 
right-angled four-sided prisms of a brown to a golden yel- 
low color, which it forms. 

Quantitative estimation. — Precipitate the uric acid 
from the solution containing it by the addition of hydro- 
chloric acid, if no albumen is present ; in case it is pres- 
ent, use acetic or phosphoric acid instead of hydrochloric. 
Let the mixture stand 36-48 hours, and collect the pre- 
5* 



106 76. BASES AND ACIDS WITH REAGENTS. 

cipitated acid on a dried and weighed filter, and add 0.045 
mgr. to the amount of uric acid found, for every cubic 
centimetre of wash-water passed through the filter. 

If hippuric acid was present, it must be dissolved out 
of this precipitate by treating it several times with alco- 
hol of 83° |„. 

HIPPURIC ACID. HCgHaNOg. 179. 

76. This acid is slightly soluble in cold Avater, but 
readily soluble in boiling water and in alcohol, and slight- 
ly soluble in ether. 

Ferric and plumbic hippurates are quite insoluble in 
water ; all others are soluble. 

Quantitatiye estimation. — Precipitate the concentrated 
solution of the acid with hydrochloric acid, and let the 
mixture stand in the cold 48 hours ; collect the precipitate 
on a dried and weighed filter, wash it Avith small portions 
of very cold water, until the washings are colorless and 
give only a faint turbidity with argentic nitrate, dry at 
100°, and weigh. For every 6 c.c. of wash-water that 
passed through the filter add 0.01 grm. to the amount of 
hippuric acid found. 

If uric acid is present, the precipitate, after being 
weighed, must be treated with alcohol, and the residue of 
uric acid weighed again. The difference between the two 
weights Avill be the hippuric acid. 

For a better method of separating the two acids see 
urine, § 113, A. 

TANNIC ACID. 

77. Tannic acid is soluble in water, alcohol, and ether; 
alkaline tannates are soluble in water, but others are diffi- 
cultly soluble. 

Reactions. — Tannic acid gives a violet-black precipi- 



77. TANNIC ACID. 107 

tate with ferric salts. It also gives a white precipitate 
when poured into a solution of gelatine ; as long as the 
gelatine is in excess, this precipitate is soluble in the su- 
pernatant liquor when heated, while if the acid is in ex- 
cess, it is much less soluble. 

If a piece of fresh skin, deprived of its hair by caustic 
lime, is left for several hours in contact with a solution 
of tannic acid, the hatter is completely absorbed, so that 
the liquid will give no color with ferric salts. 

Quantitatiyc estimation. — The tannic acid in a solution 
may be determined with considerable accuracy by com- 
paring the specific gravity of the solution before and 
after it has been in contact with powdered skin. 

The solution must be as clear as possible and not too 
dilute ; such a one wdll answer, for example, as may be 
obtained by exhausting 20 to 40 grms. of tanner's bark 
with water, and dilating to 400 or 500 c.c. 

Determine the weight of the extract obtained from a 
w^eighed quantity of the bark, and then determine the 
specific gravity of the solution accurately with the pik- 
nometer, or specific-gravity bottle (§ 34, a). Then weigh 
out 100 c.c. of the sohition in a flask, and weigh out also 
a quantity of finely divided skin, equal to about four 
times the amount of tannic acid that is supposed to be in 
this quantity of the solution ; this amount can be ascer- 
tained approximately from Table IV, taking as the per 
cent of tannic acid that w^hich is found against the 
number representing the specific gravity of the original 
solution, just determined. 

Soften the skin by soaking it in water, enclose it in a 
linen bag and press out the water, add it to the weighed 
solution in the flask, close the flask and shake the mix- 
ture vigorously, filter through a linen cloth and detennine 
the specific gravity of the filtrate. To the difference be- 
tween the specific gravity before and after treatment with 
the skin, add one, seek for the number so obtained in the 



108 78. BASES AND ACIDS WITH KE AGENTS. 

column headed specific gravity at 15° C,in Table IV, 
and against that will be found the per cent of tannic acid 
in the solution examined. A simple calculation will then 
give the per cent of the acid in the bark. 

To i^rej^are the powder of skin required in this analy- 
sis, wash a piece of sldn, that has been prepared for 
tanning by treatment with lime and other agents, with 
water, stretch it on a board, dry it with the aid of a gentle 
heat, and rasp it with a coarse file. Keep the powder in 
a well stoppered bottle. 

CELLULOSE. CioII^oOio. 324. 

78. Cellulose is insoluble in water, dilute acids or al- 
kalies, alcohol, ether, or oils. It is soluble in an amnionic 
solution of cupric oxide, and is precipitated from this so- 
lution in the form of colorless flakes. 

Strong sulphuric acid, composed of four parts of acid and 
one of water, disintegrates it at ordinary temperatures 
without coloring it, and, after a time, changes it into 
dextrine. With iodine solution this disintegrated cellulose, 
before its passage into dextrine, gives a violet-blue color. 

Quantitatiye estimation. — Cellulose is estimated quan- 
titatively by freeing it as completely as possible from all 
other substances, and weighing the residue as pure cellu- 
lose ; the best method yields results, however, that are 
about 1°|(, too high. 

A quantity of 3 to 4 grms. of the substance is exhaust- 
ed with water, alcohol, and ether, successively, as long as 
each of these solvents takes anything into solution, and 
is then macerated 10 or 12 days in a glass-stopj^ered bot- 
tle, at a temperature not above 15° C, with 12 grms. of 
nitric acid (Sp. Gr. = 1.1), and 0.8 grm. of j^otassic chlo- 
rate ; water is then added, the mixture is filtered, and 
the filter is w^ell washed, first with cold and afterwards 
with hot water : the contents of the filter are then rinsed 



79. STAECH. 109 

into a beaker and digested about an hour, at 60° C, with 
ammoniacal water containing 50 parts of water to one of 
common ammonia ; the mixture is filtered through a dried 
and weighed filter, tlie contents of the filter washed with 
the same ammoniacal water until the washings are color- 
less, then with pure Avater, with alcohol, and finally with 
ether, dried at 100° C, and weighed. 

This cellulose often contains as much as from 0.5 to 0.7 
°|g of albuminoids, and a very small per cent of inorganic 
matters. 

STARCH. CjallsoOio. 33-4. 

79t Starch, as long as it retains its natural form, is in- 
soluble in water, alcohol, and ether. In contact with hot 
water the starch grains swell up, and, if a larger quantity 
of Avater is then added, a small portion of the starch re- 
mains in solution. 

Starch may be converted into a soluble modification by 
boiling it with water under pressure, by heating it a short 
time with dilute sulphuric acid, or by the action of dias- 
tase at ordinary temperatures. 

Dry starch is colored blue or black by a solution of 
iodine in potassic iodide. The color is destroyed by alco- 
liol, potassa, or hydrosulphuric acid, or by heat ; if not 
lieated too long, the blue color reappears as the solution 
cools. 

Quantitative estimation. — Starch is usually determined 
by conversion into glucose, either by malt or sulphuric 
acid, and the subsequent determination of the glucose 
with Fehling's solution. 

1. By malt, — To prepare the extract of malt, crush 6 
grms. of fresh malt in a mortar, digest with lukewarm 
water, filter, and wash the filter with water of 60° or 70°, 
and divide the clear filtrate, after mixing it well with the 
washings, into two exactly equal parts. Mix a quantity 



110 79. BASES AND ACIDS WITH EE AGENTS. 

of the substance to be examined containing about 2.5 
grms. of starch with water, heat to 70° C, add one of the 
portions of the extract of malt, put the other portion into 
another flask, and digest both precisely alike 3 or 4 hours 
on the water-bath, at a temj^erature of about 60° or 70° 
C. Then bring both liquids to about 200 c.c. by addition 
of water, add 20 c.c. of a solution of basic plumbic ace- 
tate (§ 24, a) to each, shake vigorously, add water again 
until the volume of each liquid is exactly 500 c.c, at a 
temperature of nearly 15°, let the mixture stand until the 
solid matters settle, and then determine the glucose in an 
aliquot part of each liquid with the aid of the standard 
Fehling's solution (§ 81). 10 c.c. of that solution corres- 
pond to 0.045 grm. of starch. The two liquids will con- 
tain equal quantities of glucose, j)roduced from the malt ; 
therefore, the diflerence between the amounts of glucose 
found in the two, or the corresjDonding difference between 
the amounts of starch, will be the amount of starch in 
the substance analyzed. 

2. a. I^^ sulphuric acid. — Dry the substance thoroughly, 
and digest a quantity of it, supposed to contain about 2.5 
grms. of starch, 2 hours on the water-bath, witli 50 times 
its weight of a dilute sulphuric acid, containing V\^ by 
volume of concentrated acid, then filter, and wash the 
residue on the filter carefully. This residue is composed 
mostly of cellulose. Dilute the filtrate and washings to 
200 c.c, add about 16 c.c. of concentrated sulphuric acid, 
and digest again 7 or 8 hours on the water-bath, at 95°, 
or until a drop of the solution gives no blue color with a 
solution of iodine. If the solution is highly colored, add 
20 c.c. of plumbic acetate, shake vigorously, make the 
volume of the liquid uj) to 500 c.c, let the mixture stand 
if it is necessary to clarify the solution, and determine the 
glucose in the clear supernatant liquid with tlie standard 
Fehling's solution, 10 c.c. of which correspond to 0.045 
grm. of starch (§ 81). 



79. STARCH. Ill 

The process of previous digestion with a more dilute 
acid separates the starch more completely from the cellu- 
lose, the former being converted into the soluble modifica- 
tion, while the latter remains unchanged. {Krocker.) 

h. Wolffs s process. — Digest 2.5 to 4 grms. of the sub- 
stance with 100 c.c. of water, and 12 to 16 drops of con- 
centrated acid, 24 hours on the water-bath, then seal the 
liquid up in glass tubes and heat 12 hours in an oil-bath to 
120° C, then dilute, decolorize with plumbic acetate, and 
so on as directed in «. 

3. Dragendorff gives the following method for separat- 
ing and determining starch and the other matters with 
which it is usually associated. 

Pulverize about 2.5 grms. of the substance that has been 
dried at 100°, mix the powder with about 30 grms. of a 
solution of about G parts of potassic hydrate in 95 parts of 
absolute alcohol, and digest the mixture 24 hours at 100° C. 
in a sealed tube, or in a flnsk that can be closed air-tight ; 
filter the contents of the flask, while hot, through a dried 
and weighed filter, wash the residue thoroughly, first with 
hot absolute alcohol, then Avith cold alcohol of ordinary 
strength, and finally with distilled water, mixed with a 
little alcohol if gummy substances are present in notable 
quantity, dry the filter, first at 50°, and then at 100°, and 
weigh. The diiference between this weight and that of 
the substance taken gives the amount of albuminoids, fat, 
sugar, and a part of the mineral salts. 

The insoluble residue, with the filter torn in shreds, is 
heated with water containing 5°[q of hydrochloric acid 
until a drop of the liquid gives no blue color with solution 
of iodine, the mixture is filtered . again through a dried 
and weighed filter, dried at 100°, and v/eighed. The sec- 
ond loss of weight gives the amount of starch ; it was 
converted into dextrine by the acid and dissolved out; 
a very small quantity of mineral matters might pass into 
solution also, and, if great accuracy is required, the 



112 § SO. BASES AND ACIDS WITH KE AGENTS. 

amount of these can be determined by evaporating the 
solution of starch and inorganic salts to dryness, and in- 
cinerating the residue at a low red heat (§ 91). 

Or, the starch may be extracted with a concentrated 
solution of malt instead of with acid, in which case no in- 
organic- salts will be taken into solution. Prepare the 
solution of malt and perform the oj^eration as directed 
above. 

If much mucus is present, a concentrated solution of 
sodic chloride mixed with 5"| ^ of hydrochloric acid should 
be used instead of pure water and acid. 

GUM. 

80. The gums, which abound in the juices of plants, 
are very soluble in water, forming thick, viscid solution > ; 
they are insoluble in alcohol. 

Quantitative estimation. — This depends upon their in- 
solubility in alcohol. A quantity of from 500 to 1000 c.c. 
of the aqueous extract of the substance in whicli the gum 
is to be determined is evaporated almost to dryness on 
the water-bath, and the moist residue is digested with al- 
cohol of 80 to 85°|jj until it is no longer colored by mat- 
ters taken into solution. 

Sugar is dissolved, while gum, albuminoids, and some 
inorganic salts, remain unaffected ; collect the insoluble 
substance on a dried and weighed filter, dry at 100° C, 
and weigh. Then incinerate this residue at a low red heat 
(§ 91), and subtract from the total weight of the residue 
insoluble in alcohol, the sum of the weights of the ash 
just determined, and the albuminoids, which are deter- 
mined by another process (§ 85). The remainder may be 
considered as gum, mixed with some vegetable acids. 

GLUCOSE. GRAPE SUGAR. CeHisOeH.O. 180 + 18. 

81 . This sugar is soluble in water, and somewhat solu- 
ble in aqueous alcohol. 



§ 81. GLUCOSE. 113 

It is colored dark brown when heated with a strong so- 
lution of sodic hydrate. 

If triturated w^ith cold concentrated sulphuric acid, it 
is dissolved without being blackened. 

If a concentrated solution of glucose is mixed with co- 
baltic nitrate and a small quantity of fused caustic soda, 
the solution remains clear on being boiled. 

If baric hydrate is added to an alcoholic solution of 
sugar, a white precipitate is formed. 

If a little caustic soda is added to a solution of glucose, 
and then, drop by drop, a dilute solution of cupric sul- 
phate, a deep blue liquid is formed ; but after a few mo- 
ments a yellowish or red precipitate of hydrated cuprous 
oxide is separated. A solution containing 0.00001 of glu- 
cose will give a notable red precipitate on the addition of 
soda and a few drops of cupric sulphate ; 0.000001 of glu- 
cose in the solution gives a red tint to it with the above 
reagents. 

Quantitative estimation. — This may be effected by 
making use of the delicate reaction just described. One 
equivalent of glucose will reduce ten equivalents of cupric 
oxide to cuprous oxide ; if, then, we know the quantity 
of cupric oxide that has been reduced, we can calculate 
the corresponding amount of sugar. For this determina- 
tion, a standard solution of cupric oxide containing an 
excess of alkali is commonly used, or Fehling's solution, 
as it is often called. 

Dissolve 34.639 grms. of pure, crystallized cupric sul- 
j^hate in about 200 c.c. of water ; make another solution- 
of 173 grms. of jDure, crystallized potassic sodic tartrate 
in 480 c.c. of a solution of sodic hydrate (Sp. Gr. = 1.14). 
Add the first solution gradually to the second, and dilute 
the mixture to 1000 c.c. Each 10 c.c. of this solution 
corresponds to 0.05 grm. of glucose. Keep the solution 
in small, well-stoppered bottles, in a dark place ; the bot- 



114 § 81. BASES AND ACIDS AVITH REAGEXTS. 

ties should be filled to the top, so tliat no carbonic acid 
can be absorbed. 

Before using the solution, boil about 10 c.c. of it with 
about 40 c.c. of water, or of a dilute solution of sodic hy- 
drate if there is any reason to believe that carbonic acid 
has been absorbed ; there should not be the lea&t change 
in the liquid when subjected to this trial. 

To perform the analysis, j^ut 10 c.c. of the cuprlc solu- 
tion in a porcelain dish, and add 40 c.c. of water, or of a 
sohition of sodic hydrate if it was found necessary to 
add this in testing the solution ; heat the mixture until it 
boils gently, and allow the sugar solution, which should 
be colorless and not acid, and should not contain more 
than 'I2 to ^|/|g of sugar, to drop in from a burette or a 
pipette, graduated into ^\^^ c.c, so slowly that the boiling 
will not be stopped. After the addition of the first few 
drops, the fluid shows a greenish-brown tint ; as more sug- 
ar solution is added, the joi'ecipitate becomes more copi- 
ous, acquires a reddish tint, and subsides more speedily • 
when it presents a deep red color, remove the lamp, allow 
the precipitate to settle, and give the dish an inclined 
j^osition, so that the color of the supernatant liquid can 
be more readily distinguished over the white porcelain 
surface ; if no blue or bluish-green color is seen, probably 
enough of the solution of sugar has been added. To be 
sure, test a small portion of the clear liquid with a droj) 
of the solution from the burette ; if a yellowish-red 
precipitate appears on heating, Avhich, at first, may 
look like a cloud in the liquid, pour the contents of the 
tube back into the dish again, and continue to add the 
sugar solution until the reaction is completed. Then 
the solution in the dish should contain neither copper nor 
sugar, nor a brown product resulting from the decompo- 
sition of the latter ; filter off a portion of it while still 
hot ; the filtered liquid should have no brown tinge ; one 
portion, heated with a drop of the standard cupric solu- 



§ 82. LEVULOSE. § 83. SACCHAROSE. 115 

tion, should j^i'oduce no change in it ; another portion 
should give no red coloration or precipitate with potassic 
ferrocyanide, nor a black one with ammonic sulphide. If 
these tests do not indicate a satisfactory termination of 
the analysis, it should be repeated with a fresh quantity 
of 10 c.c. of the cupric solution. 

The amount of solution of sugar required to reduce the 
cupric oxide in this quantity of the cupric solution con- 
tained 0.05 grm. of glucose. 

Generally, the first result obtained is only an approxi- 
mation ; in the second trial, add at once nearly the whole 
amount of sugar solution required, and then test the liquid 
after each addition of two drops at a time. {Freeenius.) 

LEVULOSE. FRUIT SUGAR. CeHioOe. 

82. This sugar is very soluble in water and aqueous 
alcohol. It behaves like ghicose wdth an alkaline cupric 
solution, and is determined quantitatively in the same 
manner. 

SACCHAROSE. CANE SUGAR. Ci^H^oOn. 342. 

83. This sugar is more soluble in water and aqueous 
alcohol than glucose. 

It is not turned brown by strong alkaline solutions. 

If triturated with cold concentrated sulphuric acid, it 
is turned black, and sulphurous acid is evolved. 

If a concentrated solution of saccharose is mixed with 
cobaltic nitrate and a small quantity of fused caustic 
soda, and boiled, a violet-blue precipitate is formed. The 
presence of a very small quantity of glucose prevents the 
formation of this precipitate. 

If sodic hydrate is added to a solution of saccharose, 
and a few drops of cupric sulphate, a deep blue solution 
is obtained that remains unchanged on standing in the 
cold ; if the sodic hydrate is largely in excess, the solution 
can be boiled a short time without chano^e. 



116 § 84. BASES AND ACIDS WITH El^-.GENTS. 

Saccharose is converted into glucose and levulose when 
heated with very dilute sulphuric acid, by treatment with 
yeast, or even by long boiling of its aqueous solution alone. 

Quantitatiyc estimation* — This may be effected by first 
converting the saccharose into glucose and levulose, and 
then determining the amount of these with the standard 
cupric sohition. 

The solution, containing about 2.5 grms. of saccharose, 
is diluted to about 250 c.c, 12 drops of concentrated sul- 
phuric acid are added, and the mixture is heated 3 hours 
on the water-bath, with renewal of the water as it is 
evaporated (§ 36). If, after this operation, the solution 
has a dark color, as may often be the case, add 20 c.c. of 
the solution of plumbic acetate (§ 24, a), shake the mix- 
ture well, dilute to exactly 500 c.c, let it stand awhile, 
and use the clear supernatant liquid for the determination 
of glucose (§ 81). 

If it does not need clarifying with j^lumbic acetate, neu- 
tralize the free acid with sodic carbonate, dilute to exactly 
500 c.c, and determine glucose as above. 

10 c.c of the standard cupric solution correspond to 
0.0475 grm. of saccharose. 

In case a solution contains both glucose and saccharose, 
and it is desired to determine the amount of each, esti- 
mate the glucose at once by titration with the cupric so- 
lution ; then convert the saccharose into glucose, as above, 
and titrate the solution again ; the last determination 
gives the sum of the glucose originally in the solution 
and that which was derived from the saccharose. 

LACTOSE. MILK SUGAR. CisHsiOio. 

84. This sugar is soluble in water, but not in cold 
alcohol. 

It reduces an alkaline solution of cupric oxide like glu- 
cose, but in a different proportion. It is converted into 
glucose by dilute acids. 



§ 85. ALBUMINOIDS OR TROTEIX COMPOUNDS. 117 

Quantitative estimation. — Convert it into glucose by 
digesting its solution about 2 hours with a little sulphuric 
acid, and then determine the glucose with the standard 
cupric solution. 

10 c.c. of the solution correspond to 0.05 grin, of 
lactose. 

ALBUMINOIDS or PROTEIN COMPOUNDS. 

85. Some of these substances are soluble in water, 
others are insoluble. Most metallic salts precipitate them 
from their solutions, or coagulate the solutions, as it is 
termed. 

All of them are dissolved by boiling concentrated hy- 
drochloric acid, and the solution takes a violet color if 
access of air is allowed. 

All of them are colored yellow by concentrated nitric 
acid, and by iodine. 

They are colored red by a solution of mercuric nitrate 
(Millon's test) ; this is the most delicate test for these 
bodies ; albumen, dissolved in 100,000 parts of water, 
may be detected by this reagent. 

If a small quantity of an albuminous substance is treat- 
ed with dilute potassic hydrate, one or two drops of a 
dilute solution of cupric sulphate added, and more potassa 
until the mixture is alkaline, and the whole is well mixed 
together, a violet precipitate appears, which dissolves after 
a little agitation ; in the presence of a carbo-hydrate, as 
sugar or starch, the color is bluish, and the blue tint is 
deeper, the more of the carbo-hydrate is mixed with the 
albuminoid. {Journal far Praht. Chemie^ 102, 376.) 

When heated, these substances give off the odor of 
burnt horn or hair. 

Distinctive reactions. — Albumen is j^recipitated when 
its neutral solutions are heated to 70° C, or the solution is 
coagulated ; if alkaline, the solution needs to be neutral- 



118 § 85. BASES AND ACIDS WITH REAGENTS. 

ized by acetic acid before this reaction can be obtained ; 
if the solution is very dilute, the presence of albumen 
will be shown by a flocculent precipitate, or a mere tur- 
bidity, on being boiled. A solution of albumen is coagu- 
lated also by plumbic acetate or cupric sulphate, but not 
by acetic acid. 

Casein is not precipitated from its solutions by heat, 
except that a film is formed on the surface of the boiling 
liquid ; it is precipitated by acetic and other acids, and 
the precipitate is soluble in an excess of acetic acid. 

Fibf'ine is precipitated from its solutions spontane- 
ously, when they are removed from the influence of vital 
forces. 

Quaniitative estimation. — As it is almost impossible to 
separate all of an albuminoid from its solution or from 
matters mixed with it, pure and unaltered, or in tlie form 
of any insoluble precipitate of a definite composition, the 
amount of albuminous matters in a substance is usually 
estimated from the amount of nitrogen in it. 

Albuminoids contain, on an average, 16° |„ of nitrogen; 
therefore, the total weight of the albuminoid is VV = 6.25 
times that of its nitrogen. Assuming, then, what is gen- 
erally true, that all the nitrogen present in the dried 
plant is part of an albuminoid, we multiply the weight 
of nitrogen found in the substance by 6.25 for the weight 
of the albuminoids. 

Determination of Nitrogen. — The method most gener- 
ally applied in this case, as well as in agricultural analyses 
generally, is that of Varentrapp and Will, as modified by 
Peligot, in which the nitrogen is converted into ammonia 
by ignition with soda-lime, and the ammonia is absorbed 
by a measured quantity of a standard acid ; the ignition 
is performed in a thick-walled tube of hard Bohemian 
glass, about 40 cm. long, and 12 mm. in diameter, drawn 
out into a slender beak at one end that is bent upwards. 



§ 85. DETERMINATION" OF NITROGEN. 119 

a. First clean and dry the tube thoroughly, and seal up 
the point of the beak ; then put in the throat, where the 
beak Avidens out into the tube, a loose plug of freshly ig- 
nited asbestus ; rinse the tube out with a little soda-lime, 
about half fill it with the same reagent, freshly ignited 
and still warm, empty this soda-lime into a warm, dry 
mortar, and mix intimately with it, by gentle trituration, 
without much pressure, a carefully weighed quantity of 
from 0.2 to 0.5 grm. of the finely powdered and well-dried 
substance ; the quantity to be taken depends upon the 
richness of the substance in nitrogen ; fill about 3 cm. of 
the tube with soda-lime, and transfer this mixture into it 
from the mortar, by scooping it up carefully with the 
open end of the tube, over a sheet of dark-colored glazed 
paper ; carefully rinse the mortar and pestle into the tube 
with several small portions of the soda-lime, and finally, 
when the tube is filled to within about 4 cm. of the end, 
close it with another plug of freshly ignited asbestus, and 
rap it gently on the table several times, in order to se- 
cure an open spa(3e in the upi^er part of it for the passage 
of gases. 

h. In some cases, as in the analysis of Peruvian guano 
for example, the evolution of ammonia is liable to begin 
as soon as the substance and soda-lime are brought to- 
gether. If there is danger of this, fill about 10 cm. of 
the tube with soda-lime, which should be but very slightly 
warm, if at all, then put in the substance, fill 10 cm. more 
with the reagent, and mix the two together as rapidly as 
possible by means of a wire, bent in the form of a cork- 
screw at the end ; if this is moved backwards and for- 
wards, and twisted round a few times, through the sub- 
stance and the soda-lime, a very perfect mixture can be 
quickly made ; before taking the wire out, put in about 
10 cm. more of soda-lime, and work the corkscrew back 
and forth through this to clean it, and then fiinish filling 
the tube as in a. 



120 



85. BASES AND ACIDS WITH EEAGENTS. 



With the aid of the burette, put 20 c.c. of the standard 
vsulphuric acid in the bulbed tube C (fig. 5), and add 
water until the bulbs are about 'l^ filled; the quantity of 
the liquid should not be so great, however, as to incur any 
danger of loss when the gases evolved from the combus- 
tion-tube pass rapidly through, or when, as sometimes 




Fig. 5. 

happens, there is a sudden retrograde current towards the 
combustion-tube at the close of the operation. 

When the bulbed tube is properly filled, hold it so that 
the liquid rises higher in one arm than in the other, con- 
nect it with the combustion-tube by the soft, well-fitting 
cork, that has been already fitted to the small horizontal 
tube of the bulbed apparatus, and lay the combustion- 
tube on a level table ; if the connection is not tight, the 
acid will slowly assume the same level in both arms of 
the bulbed tube. 

The apparatus being tight throughout, and a small fur- 
nace full of live charcoal coals being ready, the combus- 
tion-tube is introduced into the iron combustion-furnace 
(fig. 5), so that only about 5 cm. of the tube remains out- 
side the furnace at B, and the whole is slightly inclined 
towards that end, so that any water, condensing in the 
small tube of the bulbed apparatus, will flow down into 
the bulb beyond. 

A movable screen bemg placed over che tube in the 
fm-nace, about 8 cm. from the end B, this end is surround- 



§ 85. DETERMINATION OF NITROGEN, 121 

ed with fresh, live coals, large coals being used to bridge 
over the top, in order that there shall be no weight there 
on the tube when softened by heat, to bend it inwards 
and close the passage above the soda-lime. 

When this part of the tube is red-hot, move the screen 
along about 8 cm., and apply more coals in the same man- 
ner as around the first 8 cm. of the tube. 

When that part of the tube is approached, where the 
mixture of soda-hme and substance is contained, care 
must be exercised in applying the coals, so as not to have 
too rapid an evolution of the gas ; there is little danger 
that any ammonia will pass through the acid unabsorbed, 
but it will be safer not to have so rapid a flow of gases that 
the bubbles in the bulbed apparatus cannot be counted ; 
nevertheless, a continuous current should be maintained, 
and, all the while, the front end of the tube must be kept 
well heated by supplying fresh coals as often as is nec- 
essary. 

When the tube has been heated throughout, and quite 
intensely around the mixture of substance and soda-lime, 
and the passage of bubbles through the acid has ceased, 
break off the point of the beak at A, and draw a consid- 
erable quantity of air through the whole apparatus by 
applying suction at the mouth of the bulbed tube, in or- 
der to carry all ammonia remaining in the combustion- 
tube into the acid ; disconnect the bulbed tube from the 
other, add a little cochineal, and then the standard sodic 
solution until the acid is almost neutralized, empty the 
contents of the bulbs into a beaker, rinse with a little 
water, and finish the titration (§ 45). 

For each cubic centimetre of the acid that Avas neutral- 
ized by the ammonia set free, the substance analyzed con- 
tained 0.014 grm. of nitrogen. 

When very great accuracy is required, the ammonia 
should be collected in hydrochloric acid, oily matters fil- 
tered out, if any are seen in the acid after the combustion 
6 



122 § 86. BASES AND^ACIDS WITH REAGENTS. 

is finished, the bulbs rinsed out with alcohol, and the am- 
monia determined with the aid of platinic chloride (§ 47, a). 
If the substance is very rich in nitrogen, it must be 
mixed with an equal quantity of jnire sugar, in order to 
avoid the danger of an impetuous retrograde current in 
the bulbed tube, when the evolution of gas ceases and 
the whole apparatus is filled with ammonia-gas. 

UREA. CII4N2O. 60. 

86. Urea is very soluble in water and alcohol, but dif- 
ficultly soluble in ether. 

Reactions. — When heated it gives off ammonia. 

Nitric or oxalic acid causes the formation of a white 
precipitate in concentrated solutions of urea. 

Quantitative estimation. — The volumetric method of 
Liebig, with mercuric nitrate, is easily and quickly exe- 
cuted and yields accurate results. 

To prepare the standard solution of mercuric nitrate, 
heat an excess of mercury with concentrated nitric acid, 
concentrate the solution, and, on cooling, crystals of mer- 
curous nitrate will be deposited ; pour off the mother- 
liquor, wash the crystals, first with dilute nitric acid, and 
then with cold water, dissolve them in pure nitric acid, 
and heat the solution until a drop of it gives no precipi- 
tate or turbidity with sodic chloride ; evaporate the solu- 
tion on the water-bath to the consistency of a syrup, dilute 
it with 10 volumes of water, let it stand 21 hours, and 
filter if any precipitate is formed. 

To determine the strength of this solution, dissolve 
10.864 grms. of pure, ignited sodic chloride in 1 litre of 
water; dilute 10 c.c. of the mercuric solution with 90 
c.c. of water, put 10 c.c. of this diluted solution in a small 
beaker, add 4 c.c, of a cold saturated solution of sodic 
phosphate, and quickly, before the precipitate caused by 
this reagent has time to become crystalline, allow the so- 



§ 86. ' UREA. 123 

Iiition of sodic chloride to flow in from a burette with 
constant stirring, until the precipitate disappears, and the 
solution becomes clear again. Each cubic centimetre of 
the sodic sohition required corresponds to 0.02 grm. of 
mercuric oxide ; on the basis of this determination, then, 
the amount of mercuric salt in the dihited solution, and 
the strengtli of the concentrated solution, can be estimated. 

Now, to bring the mercuric solution to a urea standard, 
it must be diluted so that 1 litre will contain 72 grms. of 
mercuric oxide ; dilute the solution almost to this point, 
and then compare it with a solution of urea of known 
strength. For this purpose, dissolve 2 grms. of pure 
urea, dried at 100° C, in water, dilute the solution to 100 
c.c. and put 15 c.c, of this solution in a beaker; in an- 
other small beaker, wash a few crystals of sodic bicar- 
bonate with a considerable quantity of cold water, and, 
after pouring this off, add just enough water to make a 
thin paste with the salt ; have ready also a piece of clean 
glass, with its under surface coated with asphaltum varnish. 

Now, allow the mercuric solution to flow slowly from 
the burette into the solution of urea, with the addition 
from time to time of a small quantity of dry sodic car- 
bonate, in order to nearly, but not quite, neutralize the 
nitric acid that is set free ; the solution must all the while 
have a slight acid reaction* To ascertain whether all the 
urea is precij^itated, transfer a drop of the solution, on 
the end of a glass rod, to the glass plate, and cover it 
with a drop of the paste of sodic bicarbonate ; if no yel- 
low color appears in a few seconds, wash the test-drop 
back with the smallest possible quantity of water, and, 
after adding a little more mercuric nitrate, test again with 
the sodic bicarbonate ; the first trace of a yellow color, 
that appears as soon as the two drops come together, in- 
dicates that suflicient mercuric chloride has been added. 

The standard mercuric solution is to be diluted so that 
1 cubic centimetre corresponds to 10 mgr. of urea, or to 



124 g 86. BASES AND AGIDS WITH EEAGENTS. 

0.5 c.c. of this solution of urea of known strength that 
has been prepared. 

M. Byasson {Chemical JVews Amer, Hepr., 4, 143) pre- 
pares this standard solution by dissolving exactly 72 
grms. of pore red oxide of mercury, or mercuric oxide, in 
100 grms. of nitric acid diluted with half its weight of 
water, evaporates the solution at a gentle heat until acid 
vapors appear, and then makes the volume up to one litre 
at 15° C; if the dihition causes a slight turbidity, a few 
drops of nitric acid will remove it. In this way, he states, 
a solution will be obtained in which all the mercury is 
present as mercuric nitrate, and with as small an excess of 
acid as possible ; while, if prepared by dissolving mercury 
in nitric acid, it is liable to contain mercurous nitrate. 

As this mercuric solution is also to be used, in anal- 
yses of urine, to determine the sodic chloride, it should 
also be titrated with reference to this. Take 10 c.c. of a 
solution of sodic chloride containing 2°|g of the salt or 0.2 
grm., add to it 3 c.c. of the standard solution of urea, 
prepared as above, and 5 c.c. of a cold saturated solution 
of pure sodic sulphate, and allow the mercuric solution 
to flow from the burette into this mixture with constant 
stirring, until there is a permanent turbidity in the liquid ; 
the amount of mercuric solution required for this corres- 
ponds to the 0.2 grm. of sodic chloride ; calculate the 
amount of sodic chloride that corresponds to 1 c.c. of the 
standard mercuric solution, and mark it on the label of 
the bottle. 

For the determination of urea in a solution containing 
it and free from j)hosphoric and hippuric acids, proceed 
with 15 c.c, as directed for determining the standard of 
the solution with reference to urea, after having first de- 
termined the sodic chloride, which is commonly present, 
by the amount of the standard solution required to pro- 
duce permanent turbidity ; use the dry sodic carbonate to 
maintain the neutrality of the solution, the paste of the 



§ 87. FATTY SUBSTANCES. Ir25 

bicarbonate to ascertain the point of saturation with mer- 
curic chloride, and so on in the manner already described. 

The results obtained, however, must be corrected for 
very dilute or very concentrated solutions of urea, since 
the standard mercuric solution is adapted for such solu- 
tions only as contain 2° 1^ of urea ; if the solution is more 
concentrated than this, tlie yellow color api>ears prema- 
turely ; if more dilute, it does not appear so soon as it 
should. 

If the reaction indicating saturation was obtained with 
10 c.c. or less of the mercuric solution, subtract the prod- 
uct of 0.08 into the whole number of cubic centimetres re- 
quired, fi'om this total quantity ; if the reaction was obtain- 
ed with less than 15 c.c. but with more than 10 c.c, subtract 
also, in addition to the abov^e product, the product of 0.06 
into the number of cubic centimetres required above 10 ; 
if more than 15 c.c. were required, but less than 20, sub- 
tract also, from the total amount used, the product of 0.04 
into the number of cubic centimetres above 15, in addi- 
tion to the above two products. {Rautenherg ^ Fres. Zeit- 
schrift, 4, 500.) The final remainder, multiplied into 0.01, 
will give the amount of urea in the 15 c.c. of solution 
tested. 

In case the solution is more than 2"] ^ strong, then more 
than 30 c.c. of the standard mercuric solution Avill be re- 
quired ; for each cubic centimetre of the standard solution 
used above 30 c.c, ^1^ c.c of water must be added to the 
mixture, before taking out a sample drop to be tested 
with the paste of sodic carbonate. 

FATTY SUBSTANCES. 

87. Fats are insoluble in water, somewhat soluble in 
strong alcohol, and very soluble in ether. 

Quantitative estimation. — This is effected by lieating 
the finely divided substance with 2-3 volumes of ether 



126 g 88. BASES AND ACIDS WITH HE AGENTS. 

(Six Gr. =r 0.72), evaporating the etlicrial solution of fat to 
dryness, and weighing the residue. 

Several portions of ether must be used, and the extrac- 
tion is best conducted in a flask provided with tubes like 
a washing-bottle, and which is connected with the lower 
end of a Liebig's condenser (§ 36). 

The extraction may not be considered as ended until a 
drop of the last filtrate leaves no residue when evaporat- 
ed on a watch-glass. The solutions, if not perfectly clear 
as they came from the filtering flask, should be filtered 
through paper. The chlorophyll in tlie green parts of 
plants goes into solution Avith the fat, but it may be re- 
moved by filtration through bone-black. 

The clear etherial extracts may be collected in a gradu- 
ated cylinder, and the fat determined in an aliquot part of 
the well-mixed liquid by evaporation to dryness, drying 
the residue at 100° C, and weighing. 



ALCOHOL. CoHeO. 46. 

88. Alcohol is miscible with water in all proportions. 

QuantitatiTC estimatioilo — This is efiected by distilling 
the alcohol ofi*, and estimating it in the distillate by the 
specific gravity. ^ — 

a. To 10 c.c. of the solution to be examined, which 
must contain no free volatile acid, as acetic, for example, 
add its volume of water, and subject the whole to distill- 
ation in a small flask connected with a small Liebig's 
condenser. Collect the distillate in a specific-gravity bot- 
tle with a mark on it, indicating a capacity of 10 c.c. 
When somewhat less than half the liquid has been dis- 
tilled over, remove the specific-gravity bottle from the 
tube of the condenser, bring the temperature of the dis- 
tillate to 15° C.,fill up to the mark with water, and A\'eigh. 
Knowing the weight of 10 c.c. of water at this tempera- 



§ 88. ALCOHOL. 127 

tiire (weight of 1 cubic centimetre = 0.999183 grm.), we 
can calculate the specific gravity of this distillate, that 
contains all the alcohol that was in the liquid examined, 
and from Table Y, learn the per cent of alcohol in the 
distillate. Then the per cent of alcohol by weight in the 
solution examined is readily calculated if the weight of 
10 c.c. of that solution is known. 

Griffin, in his examination of wines («/. J. Griffin^ 
Ghemical Testing of IVmes and /Spirits), used 25 c.c. 
of the alcoholic liquid, added its volume of water to it, 
made the volume of the distillate up to 50 c.c, and deter- 
mined its specific gravity. 

If the substance to be examined contains free acetic 
acid, add a little soda to the liquid before distillation. 
The distillate should have no acid reaction. 

h. The alcohol in a wine may be approximately esti- 
mated by evaporating a measured quantity to about half 
its bulk, adding water until the original volume is re- 
stored, and determining the specific gravity of this liquid ; 
then subtract the number by which this specific gravity 
is greater than 07ie, from the specific gravity of the alco- 
holic liquid itself, and take the remainder as the specific 
gravity of the mixture of alcohol and water in that liquid, 
and get the per cent of alcohol corresponding to this 
specific gravity from Table V. To illustrate the principle, 
suppose a wine is examined whose specific gravity equals 
0.9951 ; after evaporation down to one-half, and adding 
water until the original volume is restored, the specific 
gravity is 1.0089. 

0.9951 — 0.0082 = 0.9869. 

Against the specific gravity of 0.9862 in the table, the 
per cent of alcohol is found to be 0. 



128 § 89. SPECIAL METHODS OF ANALYSIS. 

CHAPTER lY. 

Special Methods of Analysis. 
1. 

COURSE or QUALITATIVE ANALYSIS. 

89. The following course of analysis is designed as 
a general guide in qualitative analytical work. Only a 
single reaction for each substance is mentioned in it, and 
that is generally the most delicate one ; for fuller de- 
tails in regard to this particular reaction, and for a few 
other ones that may in some cases be applied as confirma- 
tory tests, the student is referred to Chapter III. 

He should, before undertaking to work with the aid of 
this course, thoroughly familiarize himself, by actual ob- 
servation, with the behavior of the difierent acids and 
bases with reagents, so that he may know what is indi- 
cated by any j^articular reaction, the moment he sees it. 

The mode of working wath the aid of the scheme given 
below is best explained by an example. Suppose we have 
a solid containing CI, P^O^, SO3, K,Fe, and Mn. Begin- 
ning with 1 in the left-hand column of figures, in the course 
for the detection of the acids, the first question is, 
whether the substance is a solid or a solution. It being 
the former, we are referred, in the right-hand column of 
figures to 2 ; going then to 2, in tlie left-hand column, 
we find that the soluhlllti/ of the substance is to be test- 
ed ; Ave apply the solvents in the order there indicated, 
and find that it is soluble in dilute nitric acid, when we 
are referred to G ; going to 6, in the left-hand column, we 
get no gritty residue on evaporation to dryness, and there- 
fore no silicic acid is present ; passing on to 7, to which 
we are referred next, we get no sucli reaction as is dc- 



§ 89. coirrvST^ op qi^alitative axalys.s. 129 

scribed there, nor such ns iii 8 ; tlierefore, carbonic acid 
and sulphur are absent ; we do get, however, the fine 
white precipitate as described in 9, and note sulphuric 
acid as present ; we also get a yellow precipitate in 10, 
and make a note of phosphoric acid as present ; we do 
not get the reaction in 11, but get a wliite precipitate in 
12, the formation of which, under the circumstances, indi- 
cates tliat cyanogen, iodine, ferrocyanogen, or chlorine, 
may be present ; a i)recipitate would be given also by 
sulphur, if that Avere present, but the test for this element 
has already been made ; we do not find the first three 
substances named above, and learn in 16 that, consequent- 
ly, chlorine is present ; AVe find no nitric acid in 17, and, 
as the substance is not blackened when heated as directed 
in 18, no organic acids are present, and Ave haA^o finished 
the examination for the acids. 

Passing to the detection of the bases, Ave have the 
question in 1 already answered for us, Avith this small 
diflference, that, in the examination for the bases, a hydro- 
chloric-acid solution is preferable to a nitric-acid solution ; 
going on to 3, we add sulphuric acid, and get no reaction, 
CA^en after the mixture of substance and reagent has stood 
some time ; no lead or barium, and, at the most, only 
traces of calcium, can be present ; passing on to 7 Ave find 
no ammonium ; Ave get the violet color, indicating potas- 
sium, in 9, after having properly prepared the solution ns 
directed in 8 ; and so Avorking on, Ave find no copper in 
10, but do get iron in 11, and manganese in 15, and after 
that, nothing more before reaching the end of the course. 

It Avill be noticed that sulphuretted hydrogen and ani- 
monic sulphide, and also the blowpipe, are used but little 
or not at all in this course of analysis ; there are sufii- 
ciently good reasons why their use should be dispensed 
with, if it can be done Avithout impairing the reliabiUty 
of the work. 

The plan of the courso for the basej corresponds in the 
6* 



130 SPECIAI. METHODS OF ANALYSIS. 

main witli tliat of Zettnow. [Poggendorf s Annalen, 
103, 324.) 

The attention of the analyst is called to Table X, 
"where the average and extreme composition of agricul- 
tural materials and j^roducts are given ; by consulting 
this table he can ascertain what he may expect to find in 
any substance under examination, tliat is used in, or 
jjroduced by, agriculture, and whether or not he must 
needs work with special care, or with large quantities of 
the substance, in order that a small quantity or traces of 
any element or compound shall not escape detection. 



DETECTION OF ACID ELEMENTS AND ACIDS. 

1. a. The substance is a solution ; this solution will 

be referred to as the^rs^ solution. - - - - 6 

b. Not a solution. - ----- 2 

2. a. The substance is soluble in water, or in dilute 
or concentrated nitric or hydrochloric acid ; this 
solution will be referred to as the Jirst solution. - 6 

b. It is partially soluble in water or acids, as indi- 
cated by the residue left undissolved even after 
heating, and by the distinct residue left on evapo- 
ration of a drop of the solvent with which the 
substance has been treated. Treat a larger portion 
of the finely divided substance with another por- 
tion of the solvent, filter, and mark the filtrate F 2. 
With the contents of the filter go to - - - - 3 

c. It is quite insoluble in water or acids. - - - 3 

3. A portion of the insoluble substance, in the shape 
of a very small fragment, if possible, rather than 
a fine powder, is fused for a considerable time in a 
bead of phosphorus-salt on platinum wire ; the 



DJiTECTIOX OF ACIDS. 131 

fragment is not entirely dissolved, but remains 
visible in the bead, retaining its original form. 
Also, when the substance in powder is fused in a 
bead of sodic carbonate on the platinum wire, the 
bead froths, carbonic acid being set free. Both 
these reactions together indicate Silicic. - - - 4 

4. A small portion of the original substance, finely 
23ulverized, is made into a paste with concentrated 
sulphuric acid in a leaden tray, the tray is covered 
with a piece of Bohemian glass coated with wax, 
and from which the coating has been removed in 
a few places with a sharp-pointed instrument, and 
the whole is gently heated for about a half an 
hour. The glass is found to be corroded where 
the wax vv^as removed (see § 6(S). Fluorine. - 5 

6. The insoluble substance has black particles in it, 
that are entirely or partially consumed when heat- 
ed on platinum foil. (Coal.) Cakbox. . - - 6 

6. Evaporate a portion of the first solution or of F 2 
to dryness, after adding hydrochloric acid, if not 
already present, ignite the residue gently, moisten 
it with concentrated hydrochloric acid, let stand a 
short time, add considerable water, and digest the 
mixture. A white powder, or perhaps a reddish 
one if much iron is present, remains undissolved, 
that feels gritty under the glass rod. Soluble 
Silicic. "^ 

7. The addition of dilute sulphuric acid to a small 
quantity of the original substance causes efferves- 
cence, that accompanies the evolution of a colorless 
gas ; a drop of lime-water, suspended on the end 
of a glass rod, and held above the liquid in the 
test-tube, is made turbid. Carboxic. . . - - i 

8. In the same experiment a colorless gas is evolved, 
having an offensive odor, and blackening a piece of 



132 SPECIAL METHODS OF AjSTALYSIS. 

moistened lead-paper that is held in tlie moutli of 
the tube. (Hydrosulpliurlc.) Sulphur. - - - 9 
9. The first sohition, or F 2, after acidification with 
hydrochloric acid, if not already acid, gives a Avhite, 
finely pulverulent j^i'ccipitate with baric chloride. 

SULPIIUEIC. -10 

Sulphuric acid may be found also in the insoluble 
substance in the course of the examination for 
bases. 

10. If a very small quantity of the solution of the sub- 
stance is added to amnionic molybdate, a pale yel- 
low precipitate is formed, at once, or after some time, 
a part of which adheres strongly to the sides of 
the tube ; the precipitate is soluble in ammonia. 
Phosphoric. 11 

11. To a portion of the hot solution, containing a 
slight excess of acid, add about twice its volume 
of alcohol, and then dilute sulphuric acid or am- 
monic sulphate, and filter if any precipitate is 
formed, heat the filtrate until the alcohol is ex- 
pelled, add ammonia in slight excess, and then 
acetic acid until the ammonia is more than neutral- 
ized, and finally calcic sulphate. A fine white pre- 
cipitate appears, at once, or after some time. 
Oxalic. 12 

12. To a small portion of the dilute nitric acid solu- 
tion of the substance, or of the aqueous solution 
acidified with nitric acid, add argentic nitrate. 

a. No precipitate is formed. (Traces of cyano- 
gen or iodine may perhaps be found by applying 

the tests in 12 5, and 13.) 17 

h. A precipitate is formed. 

Treat a small portion of the original substance 
with a little dilute sulphuric acid, in a Avatch-glass, 
and quickly invert another watch-glass, with a 



DETECTION OF ACIDS. 133 

drop of ammonic sulphide, saturated with sulphur, 
in its centre, over the first one ; after a few min- 
utes evaporate this drop of ammonic sulphide to 
dryness with a gentle heat, and moisten the dry 
residue with ferric chloride. A deep red color 
appears. Cyanogeis^. 13 

13. To a portion of the aqueous solution or extract of 
the substance, add two or three drops of potassic 
dichromate, or enough to give a pale yellow color 
to the liquid, and then a few drops of concentrat- 
ed hydrochloric acid. A drop of this mixture on 
starch-paper colors it blue. Iodine. - - - - 14 

14. A portion of the first solution gives, Avith ferric 
chloride, a deep blue j^recipitate, unafifected by di- 
lute acids, but decomposed by sodic hydrate with 
the conversion of the blue color into a reddish 
one. Fereocyanogen. 15 

15. a. N'o very decided reaction was obtained in 12 

for cyanogen, 16 

h. A decided reaction v:as obtained for cyanogen. 
To the dilute nitric acid extract of the substance, 

or the aqueous extract acidified with nitric acid, 
add argentic nitrate as long as a precipitate is 
formed, filter, wash the precipitate a little, dry it, 
and ignite it gently in a porcelain crucible until it 
is fused, pour a little water and a few drops of di- 
lute sulphuric acid over the fused mass after it is 
cool, put a piece of zinc in contact with it, and let 
the whole stand, some time ; finally filter, acidify 
the filtrate with nitric acid, and add argentic ni- 
trate. 

a. No precipitate. IT 

h A white precipitate is formed ; no iodine or 
ferrocyanogen has been found. Chloeine. - - 17 
c. A precipitate is formed, but it is not white, 



134 SPECIAL METHODS Ol*^ ANALYSIS. 

or iodine or ferrocyanogcn has been found. - - 16 

10. a. The precipitate in 12 was white, and no cyano- 
gen, iodine, or ferrocyanogcn, has been found. 

Chlokine. 17 

h. Not white, or one or more of these substances 
was found ; treat the precipitate obtained in 15, or, 
if cyanogen was absent, that obtained in 12, with 
amnionic hydrate, filter, and add dilute nitric acid 
to the filtrate until acid reaction. A white pre- 
cipitate appears, which, if abundant, collects in 
curdy flakes on agitating the mixture. Chlorine. IT 

IT. Treat a portion of the original substance with a 
little dikite sulphuric acid if it is a solid, or with 
concentrated acid if it is a solution, add copper 
turnings, and heat the mixture. Red fumes are 
evolved, which may be more readily perceived on 
holding the tube over white paper, and looking 
throuGjh it leno^thwise. Nitric. - - - 18 

18. a. A portion of the solid substance, when quickly 
heated to a high temperature on ' platinum foil, is 
blackened, with separation of carbon, and an odor 

of burning organic matter is given off. - - 19 

h. Not blackened. Absence of acetic, tartaric, 
and other organic acids. Finis. - - - - B. 

19. A portion of the solid or solution gives acetic 
ether when heated with concentrated sulphuric 
acid and alcohol ; the pleasant aromatic odor of 
this ether may be most readily distinguished from 
that of common ether, which is formed at the 
same time, after the liquid has become quite cold. 
Acetic. 20 

20. To a portion of the first solution, that must be tol- 
erably concentrated, add ammonia until it is faint- 
ly alkaline, filter if not clear, add a little amnionic 



DETECTION OF ACIDS. 135 

chloride, then calcic chloride, agitate the mixture 

vigorously, and let it stand 10-20 minutes. 

a. No precipitate is formed. - - - - 21 

1). A white 2:)recipitate is formed ; filter, and mark 
the filtrate ¥. 20. Digest th.e precipitate in the 
cold, Avith sodic hydrate, with frequent agitation, 
dilute, filter, and boil the filtrate. A white gelat- 
inous precipitate is formed ; test it Avith ammonia 
and argentic nitrate (§ 71). Tartaeic. - - 21 

21. To F. 20, or to the clear mixture of original solu- 
tion and calcic chloride obtained in 20, add consid- 
erable alcohol. 

a. ]^o precipitate. Finis. - - - - B. 
h. A white precipitate is formed ; filter, Avash the 
precipitate with a little alcohol, dissoh- e it in a 
small quantity of dilute hydrochloric acid, add am- 
monia in slight excess, and boil the liquid some 
time. 

aa. No precipitate. - _ 22 

hb. A white precipitate is formed ; filter the liquid 
Avhile boiling hot, and mark the filtrate F. 21. Dis- 
soh^e the precipitate on the filter in a very little 
dilute hydrochloric acid, add ammonia in slight 
excess, and boil this mixture. A similar Avhite 
precipitate is formed again. Citric. - - - 22 

22. F. 21, or the solution obtained in 21 that gaA'e no 
precipitate on boiling, may contain malic acid. 
Add considerable alcohol to it. 

a. No precipitate is formed. Finis. - - B. 
h. Awhite precipitate is formed. Probably Malic. 
To be sure, treat the precipitate Avith acetic acid, 
- add alcohol, filter the liquid if not clear, add plum- 
bic acetate to the filtrate, and ammonia until the 
liquid is neutral, filter out the precipitate, Avash it, 



136 SPECIAL METHODS OF ANALYSIS. 

suspend it in water through which a current of 
sulphuretted hydrogen is passed, filter, evaporate 
the filtrate to dryness on the water-bath, and heat 
the residue, supposed to be malic acid ; maleic 
acid should be formed (§ 73). - - - - B. 

B. 

DETECTION OF THE BASIC ELEMENTS. 

1. a. The substance is a solution, or it is soluble in 
water, or dilute or concentrated hydrochloric or 
nitric acid. This solution will be referred to as 

t\\Q first solution. 3 

h. Not soluble, or only partially soluble ; separate 
the soluble from the insoluble part by filtration ; 
this filtrate will be referred to as thej^rs^ solutio7i. 2 

2. This insoluble substance was found, in the exami- 
nation for acids, to consist entirely of carbon. - 3 
Not. Dry it, mix it intimately with four parts of 
potassic and sodic carbonate, and a little sodic ni- 
trate, fuse the mixture 10-20 minutes on platinum 
foil, and exhaust the fused mass with hot water; 
decant off this aqueous extract, wash the residue 
once or twice by decantation, then treat it with 
very dilute hydrochloric acid, and evaporate the 
mixture to dryness ; moisten this second residue 
with concentrated hydrochloric acid, and, after a 
while, add water, heat, and finally separate this 
acid solution from the insoluble silica, by filtra- 
tion. 

Acidify the aqueous extract of the fused mass, ob- 
tained above, with hydrochloric acid, and test a 
small portion of it for sulphuric acid with baric 
chloride ; if a fine white precipitate is formed, and 
lead or barium is subsequently found among the 



DETECTION OP THE BASIC ELEMENTS. 137 

basic elements, the insoluble substance was com- 
posed, at least in part, of plumbic or baric sul- 
phate ; if lead or barium is not found, but calcium 
is, then the insoluble substance consisted, at least 
partly, of calcic sulphate, which requires considera- 
ble water or dilute acid for its complete solution ; 
if no sulphuric acid is found, the insoluble sub- 
stance contained only silica or silicates, besides, 
possibly, a fluoride and carbon. 
Mix the acid solution, filtered from the silica as 
above, and the remainder of the aqueous extract 
together, and without filtering out any precipitate 
- that may be formed, proceed with the analysis as 
in 3, if it is desired to analyze this solution sepa- 
rately, in order to ascertain the composition of the 
insoluble part of the substance ; but it will not be 
found, in any case, to contain arsenic or ammoni- 
um, nor will copper or zinc be likely to be found 
in it, and not in any case unless it contained silica ) 
lead and barium may be present as sulphates, and 
the latter possibly as a silicate. 
Potassium and sodium cannot, of course, be tested 
for in this solution ; if it is desired to examine the 
insoluble substance with respect to the presence of 
these metals, the silicate must be attacked with 
hydrofluoric acid or a fluoride, in the manner di- 
rected for the quantitative analysis of silicates. 
(§ 58, c.) 

If it is not necessary to analyze this solution sepa- 
rately, it may be mixed at once with the frst solu- 
tion, Yeserxmg, however, a portion of this latter 
for the examination for the alkaline metals. - - i 

3. Heat a portion of the nearly neutral, first solution 
to boihng, add to it about its volume of alcohol, 
or twice its volume if the solution is very dilute. 



138 SPECIAL METHODS OF ANALYSIS. 

and then add dilute sulphuric acid as long as a pre- 
cipitate is formed. 

a, No precipitate is formed, even after vigorous 
agitation and some time ; expel the alcohol from 
the liquid by boiling it a few minutes, and mark it 

F. 3. 7 

h. A white precipitate is formed ; let the mixture 
stand awhile, filter the liquid while hot, boil the 
filtrate a few minutes to expel the alcohol, and 
mark it F. 3. - - - - _ . 4 

4. Agitate the precipitate obtained in 3 vigorously 
with considerable water, filter, and add ammonic 
oxalate to the clear filtrate. A white precipitate 
indicates Calcium. - - _ - - 5 

5. Treat the contents of the filter in 4 with ammonic 
tartrate, heat gently, filter, acidify the filtrate 
with acetic acid, and add a little potassic dichro- 
mate. A yellow precipitate indicates Lead. - 6 

6. Wash the residue on the filter in 5 well, boil it 
about 10 minutes with 8-10 times its bulk of sodic 
carbonate, add water, filter, Avash the contents of 
the filter very carefully, pour a little dilute hydro- 
chloric acid over this residue, and add calcic sul- 
jihate to the solution that passes through. A fine 
white precipitate, or a turbidity, indicates Barium. 7 

7. Put about a third of F. 3, or a corresjionding 
amount of the first solution, into a small flask, add 
baric hydrate as long as it gives a precipitate, and 
then a little more, so as to be sure of an excess, 
heat the mixture, and hold a piece of moistened 
red litmus-paper or yellow turmeric-paper in the 
tube. The paper is colored blue or brown. Am- 
monium. - - -.- - - - -8 

8. Heat the mixture in 7 until all or nearly all the 
ammonia is expelled, filter, add a little baric hy- 



DETECTION OF THE BASIC ELEMENTS. 139 

drate to the filtrate, to be sure that no further pre- 
cipitation will be produced, then add amnionic 
carbonate as long as a precipitate is formed, avoid- 
ing, however, a great excess of the reagent, heat 
and filter, and evaporate the filtrate nearly to 
dryness. 

A drop of this filtrate, evaporated to dryness in 
the platinum wire loop, gives a yellow color to the 
flame of a Bunsen's gas-burner. Sodium. - - - 9 
9. In a similar experiment the flame is violet, or vio- 
let-red when seen through blue glass. Potassium. 10 

10. To a small portion of F. 3, add ammonia very 
carefully until the free acid is just neutralized, and 
then a httle ammonic sulphide, drop by drop, with 
constant agitation, and heat the mixture. 

a. No precipitate is formed at any time. (Traces 
of copper, arsenic, iron, and manganese, may per- 
haps be found by applying the tests described in 
10 b, 1:2, 14, and 15 ^). 18 

h. A precipitate is formed. 

To a small portion of F. 3, add ammonia until the 
well-mixed liquid smells strongly of the reagent, 
and let the precipitate settle if any is formed. The 
clear supernatant liquid is blue. Copper. - - 11 

11. In the same experiment a red flocculent precipi- 
tate is obtained, the color of which may, however, 
not appear, in case much copper is present, until it 
has been collected on a filter and washed a few 
times. Iron. 1^ 

12. If copper has been found in notable quantity, put 
the remainder of F. 3 in a small flask, add two 
or three pieces of pure zinc, and close the flask 
with a perforated cork, in which is a glass tube 
drawn out to a fine jet. 



140 SPECIAL METHODS OF A:N^ALYbIS. 

If copper was not found, take only a small part of 
F. 3 for this trial. 

Care must be taken not to inhale the gas from the 
flask, if there is any reason to suspect that arsenic 
is present. 

After the hydrogen has been evolved a few min- 
utes, wrap a towel around the flask, ignite the jet 
of gas, and hold a cold porcelain surface in the 
flame. Black lustrous spots are deposited on the 
porcelain surface where the flame comes in contact 
with it. Arsenic. 13 

13. a. Copper was not found, and only a small portion 

of F. 3 was taken for the test in 12. - - - 14 
h. Copper was found, and a large j^ortion of F. 3 
is under examination. Allow the action of the 
zinc to continue 10-15 minutes, or until all the cop- 
per is precipitated ; a much longer time may be re- 
quired if the solution contains a notable quantity 
of nitric acid ; finally filter the liquid from the pre- 
cipitated metal, and mark the filtrate F. 13. - - 14 

14. Add a little nitric acid to a 2:>ortion of F. 13, or of 
F. 3, if there is no F. 13 and the first solution did 
not already contain free nitric acid in excess, and 
heat the mixture to boiling. 

a. An unmistakable reaction for iron was obtained 

in 11. 15 

h. Not. To a small portion of this solution add 
potassic sulphocyanate. A deep red color appears. 
Ieox. -..-_- . - 15 

15. To a large portion of the solution obtained in 14, 
add amnionic carbonate in excess. 

a. The precipitate which may have been formed 
at first is entirely re-dissolved by the excess of the 
reagent, and tlie solution remains quite clear, even 
after a hot digestion of 12 hours. - - - 17 



DETECTIOX OF THE BASIC ELEMENTS. 141 

h, Not. Filter the precipitate out, wash it with 
hot water, dry a large portion of it, and mix it in- 
timately with three or four times its bulk of a mix- 
ture of equal parts of potassic and sodic carbon- 
ate, and of potassic or sodic nitrate, and fuse the 
mixture Avell on platinum foil. The fused mass is 
bluish green. Manganese. 

If the substance contains little or no copper or 
iron, this reaction for mangcmese may sometimes 
be obtained with the original substance, wdien not 
obtained here (§53). 16 

16. Boil the fused mass on the platinum foil with two 
or three cubic centimetres of water, until it is loos- 
ened from the foil, filter, add dilute nitric acid to 
the filtrate, drop by drop, as long as any efferves- 
cence is produced, and then add ammonia very 
slowly and carefully, until, after stirring well, the 
liquid has a faint alkaline reaction ; heat the mix- 
ture a few minutes, and let it stand a long time in 
a warm place, if no precipitate appears at first. A 
white flocculent precipitate is formed, at once, or 
after some time. Aluminium. - - - 17 

17. To anolher portion of the first solution add sodic 
hydrate in excess, boil, and filter ; to the filtrate 
add a few drops of ammonic carbonate, and then 
ammonic chloride in excess, boil the mixture as 
long as any odor of ammonia is given off, and a 
portion of the filtered liquid gives no further pre- 
cipitate on being boiled still more ; filter the 
w^hole, and add potassic ferrocyanide to the filtrate. 

A white precipitate or a turbidity appears. Zinc. 18 

18. a. The substance contains no phosphoric acid, or 

only traces of it. - 19 

h. It does contain a notable quantity of this acid. 
Add ferric chloride to another portion of F. 13, or 



142 SPECIAL METHODS OF ANALYSIS. 

to a corresponding quantity of F. 3, if there is no 
F.' 13, until a drop of the mixture gives a reddish 
preci])itate witli ammonia. - - - - 19 

19. To the sohition to which Fe.^Cl3 has been added 
(18), or to the remainder of the filtrate F. 13, if 
no P2O5 was present in the substance, or to a cor- 
responding quantity of F. 3, if there is no F. 13, 
add amnionic carbonate until a slight permanent 
precipitate remains after vigorous stirring ; if no 
precipitate appears, the reagent may be added un- 
til it is in slight excess, and the solution is faintly 
alkaline. 

a. No ferric salt has been added to the solution, 
and it remains quite clear, or only a fine white pre- 
cipitate is formed after boiling it. - - - 20 
h. Aflocculent precipitate is formed ; heat the so- 
lution to boiling, add a boiling solution of sodic 
acetate as long as a precipitate is formed, and fil- 
ter the hot liquid immediately ; mark this filtrate 
F. 19. - - - 2G 

20. a. Calcium has been found. - - - - 21 
h. Not. To test for traces of the metal, add am- 
monic sulphide to the filtrate from the precij^itate 
by sodic acetate, or, if this precipitation was not 
found to be necessary in 19, to the liquid contain- 
ing amnionic carbonate in slight excess, after acidi- 
fication with acetic acid if not clear, filter out any 
precipitate that may be formed, and add ammonic 
chloride and oxalate to the filtrate ; a fine white 
precipitate, insoluble in acetic acid, indicates Cal- 
cium (traces). 21 

21. Add amnionic chloride and carbonate to F. 19, or 
to the liquid already containing ammonic carbon- 
ate in slight excess, and which gave no flocculent 
precipitate with the reagent, boil the mixture, fil- 



DETECTION OF THE BASIC ELEMENTS. 14^ 

ter, add ammonia in excess to the clear and cooled 
filtrate, filter again if this reagent produces any 
precipitate, add hydric disodic phosphate to the 
filtrate, agitate the mixture vigorously, and set it 
aside for several hours if no precipitate appears at 
first. A white crystalline precipitate appears, 
that, if formed slowly, adheres to the sides of the 
tube ; Avith the magnifying glass, and usually with 
the unassisted eye, the crystals are seen to be slen- 
der prisms. Magnesium. 
Finis. 



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&- cj 2 -' 

o - ^ ^- 



<10gg-^l 



2 ^ t: -r; j:; fe ^^ i: -^ r. 



o > o 



bj) 



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«3 o'S 2 ,. . 






5^ 


CO 







§ 89. OCCUKREXCE OF SUBSTANCES. 145 

C. 

For the mode of occurrence of the substances for whose 
detection directions are given in the preceding pages, in 
agricultural materials and products, consult Table X, ex- 
cept in case of the following, which are not widely dis- 
tributed, or whose occurrence presents comparatively less 
interest, because they have not been quantitatively esti- 
mated in these materials or products. 

Acid, acetic, besides occurring in vinegar, which re- 
sults from the action of the air on alcoholic liquors, is 
found among the products of the putrefaction, or of the 
destructive distillation of organic matter. 

Acid, citric, is found in lemons, and in most other acid 
fruits, such as gooseberries, cherries, etc. 

Acid, lactic, is the acid of sour milk, and is found also 
in some animal juices, and sometimes in urine. 

Acid, malic, is found in unripe apples, and in most un- 
rij)e fruits, together with citric acid, and also in potatoes, 
in many roots, and in the stems and leaves of many 
plants, such as rhubarb, tobacco, etc. 

Acid, tartaric, is found, like malic acid, in many fruits, 
and particularly in the grape ; it occurs also in the roots, 
stems, and leaves, of many plants. 

Arsenic may be found occasionally in superphosphates, 
where it was derived from the sulphuric acid used in the 
manufacture of the article ; it is also a frequent and dan- 
gerous ingredient of bright green pigments. 

Barium may sometimes be found as a silicate in some 
common rocks, and hence in soils. 

Copper may sometimes be found in culinary products 
where vessels made of the metal or its alloys have been 
used; it is a frequent and harmful ingredient of bright 
green pickles 

7 



146 § 89. SPECIAL METHODS OF ANALYSIS. 

CyanOj^en is sometimes to be fomid among the products 
of the decomposition of nitrogenous organic matter in 
the presence of strong bases, particularly if the decom- 
position has been aided by heat. 

FciTOCyanogen is a product of the decomposition of 
nitrogenous animal matters by heat, in the presence of a 
strong base and iron. 

Iodine is very widely but sparingly diffused. 

Lead may sometimes be found in water that has been 
in contact with it, and in superphosphates ; in this latter 
case it is derived from the sulphuric acid used in the 
manufocture of the fertilizer ; it is also a common ingre- 
dient of pigments. 

Manganese occurs in nearly all soils, and is generally 
found, at least in traces, in plants, and whatever is j^ro- 
duced from them. 

Zinc may occur in soils in the neighborhood of beds of 
zinc ore, and in the ashes of plants grown on such soils. 

II. 

SPECIAL METHODS OF QUANTITATIVE SEPAKATION OF 
SUBSTANCES. 

Under this head a few special methods of quantitative 
separation of substances, that often occur in agricultural 
chemical analysis, are described with full details and di- 
rections, and in a manner convenient for reference. In 
this way much repetition is avoided in the chapters treat- 
ing of special analyses. 

By consulting Table X, at the close of the book, the 
analyst may ascertain how much he will probably find of 
each of the constituents of the compound he is about to 
analyze, and, knowing the strength of his reagents, he 
can form some idea as to the quantities of these to be used 
to produce complete precipitation. 



§ 90. DESICCATION. 147 

DESICCATION. 

90. One of the more frequent determinations in agri- 
cultural analysis is that of water, ash, and organic matter. 

In the elimination of water, or the desiccation of the 
substance or solution, the object may be to determine the 
hygroscopic water of the substance, or it may be the 
estimation of the total amount of solid matter in a solu- 
tion. 

a. For the estimation of hygroscopic moisture^ dry the 
substance well in the air, so that it simll be thoroughly 
air-dried^ or under a bell-jar over sulphuric acid, as may 
be directed in each special case ; then heat a weighed 
quantity of it in a watch-glass in the steam or air-bath to 
the temperature indicated in each case, as long as it loses 
weight ; while weighing the substance, it should be en- 
closed between two watch-glasses that fit well together 
by their ground edges. 

h. Sometimes, as in the case of gypsum containing no 
volatile matters but water, the substance can be ignited 
at once in a covered crucible. A gentle heat should be 
applied at first, and the temperature should be gradually 
raised, at least almost to a red heat in some cases. 

c. When the substance contains a large amount of wa- 
ter, as in the case of the green parts of plants, it is best 
to dry a large, weighed quantity in a drying-chamber, at 
from 60° to 80° C, determine the loss of weight at this 
temperature, and then proceed as in «, with from 3 to 6 
grms. of this partly dried substance. 

d. Sometimes the substance to be dried contains other 
volatile ingredients, as ammonia for example ; in this 
case the desiccation must be performed in a current of 
dry air, or an inactive gas, like hydrogen, by means of 
which the volatile products are carried into some absorb- 
ing solution. Procure a deep water-batn, through which 
a tube of the same material passes laterally, and projects 



148 § 90. SPECIAL METHODS OF AN"ALYSIS. 

a little beyond the sides ; weigh the substance out in a small 
porcelain or platinum boat, and insert the boat in a glass 
tube open at both ends, and drawn out and bent down at 
one end ; put this glass tube in the copper tube of the wa- 
ter-bath, immerse the end of the glass tube, that is bent 
downwards, in a measured quantity of standard sulphuric 
acid, and connect the other end with an apparatus from 
Avhich dry hydrogen is evolved. Apply heat to the water- 
bath, and when the desiccation is completed, remove the 
boat, rinse the glass tube into the flask containing the 
acid, boil the acid a little to expel carbonic acid, that 
might have been carried over with the ammonia, and 
titrate with soda solution in the usual manner (§ 45, c). 

6. For the estimation of the amount of solid substances 
in a solution, evaporate a measured or weighed quantity 
on the water-bath, and dry the residue at the temperature 
indicated in each particular case ; this temperature may 
range all the way from 100° to 180° C. 

f. If the liquid contains other volatile matters besides 
water, as in the case of urine, which may give off am- 
monia when heated, put it in a porcelain or a platinum 
boat, which has been previously about two-thirds filled 
with coarsely pounded and well-washed glass or coarse 
quartz sand, dried at 100°, and weighed, and carry on the 
evaporation as in the case of a solid evolving ammonia 
when heated {d). 

g. If i:he solution contains substances that are decom- 
posed at a temperature above 100°, and yet it is difficult 
to dry the residue left on evaporation of the liquid thor- 
oughly at that temperature, imbed the dish containing 
the residue in sand that is heated to 100° C, put the 
whole over a dish of concentrated sulphuric acid under 
the receiver of the air-jjump, and exhaust the air ; after 
the sand has cooled, repeat the process with a fresh quan- 
tity of heated sand, and so on as long as there is any loss 
of weight. 



§ 91. INCIXERATION. 149 

h. If the substance in solution is liable to form hard 
clumps on drying that retain water mechanically enclosed, 
and yet the residue cannot be heated much above 100 C, 
mix it with ^ |^ or ^ 1^, of its weight of rather finely pulver- 
ized crystallized gypsum, or of pure ignited baric sul- 
phate, that has been artificially prepared, or with 3 or 4 
times its weight of well-washed fine sand. If gypsum is 
used, it should be tested beforehand, to see whether it 
loses any weight at 100°. The mixture should be well 
stirred as the evaporation approaches dryness. Heat the 
residue at 100° in the usual manner as long as it loses 
weight. 

INCINERATION, OR ESTIMATION OF ORGANIC MATTER. 

91. The dried residues obtained in the jjreceding sec- 
tion are often examined for organic matter by ignition 
until this matter is burned away, or incineration. 

a. The ignition is performed in a platinum dish or cru- 
cible at as low a temperature as possible, with provision 
for the access of air to the substance along the surface of 
the lid of the crucible, as directed for the incineration of 
filters (§ 40) ; or a piece of platinum foil may be bent so 
as to rest on the bottom of the dish and on the rim, and 
extend some distance beyond the latter. 

b. A portion of the original solid substance may be in- 
cinerated at once in the muffle furnace, as described in 
§ 123, c, under preparation of the ash of plants for analy- 
sis. Then, on subtracting from the loss of weight in this 
trial the amount of water in the quantity of substance 
taken, as may be calculated from the results of the esti- 
mation of hygroscopic water in another portion of the 
substance, the remainder will be the organic matter, or 
other volatile matter besides water. 

c. A part of the carbon sometimes obstinately resists 



150 § Pl- SPECIAL METHODS OF ANALYSIS. 

combustion ; to eliminate this, one of two courses may- 
be followed. 

1. Exhaust the mixtm-e of ash and coal with hot water, 
collect the insoluble part on the filter, wasli, dry, and ig- 
nite it ; the coal will generally be found to burn much 
more readily after this treatment, and the ash can more- 
over be heated to a higher temperature than before with- 
out fear of loss. Add the ash so obtained to the aqueous 
extract and washings, evaporate to dryness, ignite gently, 
and weigh. 

2. Or, weigh the mixture of ash and unconsumed car- 
bon, determine carbonic acid (d) in the whole or a por- 
tion of it, collect what is insoluble in the nitric acid in the 
determination of the carbonic acid, on a dried and weigh- 
ed filter, wash it well, dry at 110° C, weigh, ignite until 
the carbon is completely burned, and weigh again. The 
loss of weight gives the unburned carbon in that portion 
of the original ash taken ; calculate the amount of coal 
for the whole quantity of the original mixture of ash, 
including carbonic acid and coal, and deduct it from the 
same. 

d. A portion of the carbon in the oi'ganic part of the 
substance ignited may remain behind in combination with 
the metallic oxides as carbonic acid ; since this does not 
23roperly belong to tlie ash or inorganic part of the sub- 
stance, it should be determined and deducted from the 
total weight of the ash. 

For this purpose estimate the carbonic acid (§ 60) in a 
portion of the ash, or the whole of it, according to the 
quantity in hand, calculate the amount for the whole 
quantity of the ash, if only a portion was used for the 
analysis, and deduct it from the same. 

A substance may, however, contain a notable quantity 
of carbonic acid before ignition, as, for example, a soil 
with carbonate of lime in it. In this case the ignited 
residue should be moistened with amnionic carbonate, 



§ 91. QUANTITATIVE METHODS. 151 

carefully dried, gently ignited, and weighed, and the 
oj^eration must be repeated as long as there is any gain in 
weight, in order to be sure that there is at least as much 
carbonic acid in the substance after ignition as before. 
Then determine carbonic acid in the ash, or a portion of 
it, and in a portion of the original substance ; the excess 
in the ash over what Avas in the quantity of substance 
taken is to be subtracted from the weight of the ash. 

e. Small quantities of organic matter, as in water, may 
be determined by the following volumetric process {Kubel, 
Fresenius's Zeitschrift^ 6, 252). 

Dissolve about 0.4 grm. of crystallized potassic per- 
manganate in 1 litre of water, and also 0.398 grm. of pure 
oxalic acid in 1 litre of water. 

Put 100 c.c. of distilled water and 10 c.c. of a dilute 
sulphuric acid, containing 30 grms. of concentrated acid 
in 100 c.c, in a flask of about 300 c.c. capacity, heat the 
mixture to boiling, add 3-4 c.c. of the permanganate so- 
lution, boil the red liquid 5 minutes, remove the lamp, and 
add 10 c.c. of the solution of oxalic acid ; potassic per- 
manganate is then cautiously added from a burette or pi- 
pette, with constant stirring, until a faint red color ap- 
pears throughout the liquid. The total amount of 
permanganate added, corresponding to the 10 c.c. of the 
oxalic acid solution, = 2 milligrammes. 

Now, to make a determination of organic matter in a 
sample of drinking water, for instance, boil 100 c.c. of the 
water in a flask of 400 or 500 c.c. capacity, down to " I3 its 
initial volume, to decompose aminoniacal compounds that 
are very liable to be present in such a water, by means of 
the calcic carbonate that is also nearly always present ; 
add distilled water until the original volume is nearly re- 
stored, and 10 c.c. of the dilute sulphuric acid ; heat to 
boiling, add 5 or 6 c.c. of the permanganate solution, and 
boil 5 minutes, whereby the red color should not be de- 
stroyed ; then add 10 c.c. of the oxahc acid, and restore 



152 § 92. SPECIAL METHODS OF ANALYSIS. 

the red color by adding the permanganate solution from 
the burette as before. The permanganate added this time 
is consumed in oxidizing, not only the 10 c.c. of oxalic 
acid that was added to the solution, but also other organic 
matter, and therefore more permanganate will be required 
than when the oxalic acid was mixed with distilled water, 
as in the first experiment. Multiply the number of milli- 
grammes of permanganate in this additional quantity of 
the solution used, by 5, for the organic matter, expressed 
in milligrammes. The determination is only an approxi- 
mate one, since different kinds of organic matter require 
difierent amounts of oxygen for their complete oxidation, 
while in the above estimation it is assumed that the same 
amount is consumed by the same quantity of organic mat- 
ter of whatever kind. 

92. Estimation of Sulphur [and Chlorine) in Organic 
Compounds. 

Fuse 2 parts of a mixture of pure caustic potassa 
free from sulphuric acid (or chlorine) with ^|g part of pure 
potassic nitrate in a silver dish, with the addition of a 
little water. When the mixture is cold, add 1 part (3 to 
4 grms.) of the finely pulverized substance, fuse the 
whole with constant stirring Avith a silver spatula, and 
continue the application of the heat until the mass has 
become quite white ; if it does not readily become so, a 
little more potassic nitrate may be added. 

Dissolve the fused substance in dilute nitric acid, evap- 
orate to dryness, and eliminate silica (§ 58, a, 1), and in 
the filtrate from this, precipitate the sulphuric acid, into 
which the sulphur in the original substance has been con- 
verted by oxidation, with baric chloride (§ 59), or with 
baric acetate, if chlorine is to be determined in the filtrate 
from the baric sulphate ; the chlorine in this filtrate is 
precipitated by argentic nitrate (§ 63, a). 

93. /Separation and deter ini nation of Potassium^ Sodi- 



§ 93. QUANTITATIVE METHODS. 153 

um^ Calcium^ Magnesium^ Aluminium^ Iron^ and Man- 
ganese, and Phosphoric and Sidj^huric acids. 

This is one of the most frequently recurring separations 
in agricultural chemical analysis. 

For the best general method of separation in each par- 
ticular case, the analyst will be referred to one of the ta- 
bles at the end of this section, in which the whole course 
to be followed will be marked out in a few words, while 
more detailed descriptions will be given in the following 
paragraphs of some of the necessary mani])ulations men- 
,tioned in the table. 

A. Precii)itation of alumina, xWfi^^J^errlc oxide, Fefi^, 
Sind phosphoric acid (anhydride), PjO^, and estimation of 
the two bases. 

If the substance contains a notable proportion of or- 
ganic matter, this should first be destroyed in the solu- 
tion, and the iron completely oxidized to ferric oxide at 
the same time, by treatment with an active oxidizing 
agent. 

This oxidation may be effected by passing chlorine gas 
through the solution until it is nearly saturated ; if this 
course is followed, the solution should be heated after- 
wards, until the excess of chlorine is entirely exj^elled. 

Or, instead of using chlorine, the solution may be evap- 
orated nearly to dryness, and sodic or potassic hydrate 
added in slight excess, and sodic carbonate and a little so- 
dic or potassic nitrate ; then dry the mixture completely 
in a platinum dish, and ignite tlie residue gently until the 
organic matter is destroyed ; exhaust the mass with water, 
treat it with dilute hydrochloric acid, add this solu- 
tion and the washings to the aqueous one, and proceed as 
directed below for the estimation of ferric oxide, etc. If 
a residue remains that is insoluble in hydrochloric acid, 
dry, ignite, and weigh it, and add the amount to the 
silicic acid already obtained. 



154 § 93. SPECIAL METHODS OF ANALYSIS. 

1. Case in which there is enough alumina and ferric 
oxide present to combine vnth all the phosphoric acid. 
The filtrate from the precipitate by sodic acetate, obtained 
ill a qualitative test in the manner described below, gives 
no reaction for phosphoric acid with aramonic molybdate. 

To the not too concentrated solution add sodic carbon- 
ate with constant stirring, until a few scattered flakes of a 
precipitate remain permanent, heat to boiling, remove the 
lamp, and add immediately an excess of a boiling hot so- 
lution of sodic or ammonic acetate ; this reagent precipi- 
tates all the Al,03, Fe^O^, and P„0^ ; filter rapidly while 
hot, and wash the contents of the filter with boiling water, 
containing a little ammonic acetate ; dissolve the precipi- 
tate, without drying it, in hot, dilute hydrochloric acid, 
wash the filter out well, mix the solution and washings by 
vigorous stirring, add water, if it is necessary, to bring 
the liquid to such a volume that it can be conveniently 
divided in two equal parts, and mix carefully again by 
stirring, divide it accurately, precipitate one part with 
ammonia in slight excess, as directed for the precij^itation 
of alumina (§ 51), filter, wash with hot water, dry, ignite 
precipitate and filter separately, and weigh ; the result, 
multiplied by two, gives the total amount of Af^O^, Fe^O^, 
and PqO^ in the undivided solution. 

Reduce the ferric to ferrous oxide in the other half of 
the solution, and estimate the iron with j)otassic j^erman- 
ganate (§ 52, 5) y or, as a sulphuric-acid solution is better 
adapted for that process, this half of the solution may be 
precipitated with ammonia also, and the precipitate wash- 
ed, and dissolved, without drying it, in dilute sulphuric 
.acid. The amount of ferric oxide being estimated from 
the result, multiply by two and thus get the quantity of 
Fe^Og in the undivided solution. 

The difierence between the total weight of Al^O^, 
Fe^Og, and P„0^, and the sum of the Fe./)^, as determined 
above, and the ^fi^ to be determined in another portion 



§ 93. QUAXTITATIVE METHODS. 155 

of the solution and estimated for the amount of solution 
taken for this analysis, will give the Al^Oj. 

2. In case there is not Fe„03 and Al.^Og enough present 
to combine icith all the phosphoric acid^ more iron must 
be added, until a drop of the liquid, on a watch-glass, 
gives a reddish precipitate with a Uttlc ammonia, and the 
amount of iron so added is to be subtracted from the total 
amount found subsequently. This addition of iron is 
most conveniently made in the form of a carefully meas- 
ured quantity of an accurately titrated solution of ferric 
chloride (E>,Clg), about '1^ the strength of the reagent or- 
dinarily used. Proceed then as in 1. 

B. The method of removing phosphoric acid by means 
of metallic tin admits of the determination, in a conven- 
ient manner, of tliis acid, and alumina, ferric oxide, man- 
ganous oxide, lime, and magnesia, in the same portion of 
the solution. 

On evaporating to dryness to remove silica, after moist- 
ening the dried residue Vv'ith concentrated hydrochloric 
acid in the usual manner, add nitric acid, dilute with 
water, filter, wash the insoluble silica on the filter, evap- 
orate the filtrate and wasliings nearly to dryness, or until 
all the hydrochloric acid is expelled, dissolve the residue 
in concentrated nitric acid, heat the solution to boiling in 
a beaker covered with a large watch-glass or an inverted 
funnel, and add pure tin iii small grains, and in small 
portions at a time, to an amount about six times as great 
as that of the phosphoric acid supposed to be present, di- 
gest the mixture 5 or 6 hours in a warm place, dilute and 
decant the clear supernatant liquid on the filter, and wash 
the preci^^itatie, containing stannic oxide, stannic j^hos- 
phate, and perhaps some alumina and ferric oxide, several 
times by decantation with boiling dilute nitric acid, and 
finally with a little water ; then digest it with amnionic 
sulphide, wash the undissolved aluminic hydrate and fer- 
rous sulphide first with hot amnionic sulphide, and then 



156 § 93. SPECIAL METHODS OF ANALYSIS. 

with water to tlie successive portions of which less and 
less amnionic sulphide is added ; dissolve it in dilute hy- 
drochloric acid, and add the sohition to the first filtrate 
from the stannic oxide, etc., containing the main part of 
the alumina and ferric oxide. 

The solution obtained by treating the precipitated 
stannic oxide and phosj^hate, etc., by ammonic sulphide, 
contains all the phosphoric acid {Baeher^ Zeitschrift filr 
die gesammten Naturwissenscliaften^ 18G4, 293. Fresenius's 
ZeitscJirift, 4, 122) y if its volume has been increased to a 
considerable bulk by the washings of the precipitate of 
aluminic hydrate and ferrous sulphide, concentrate it by 
evaporation, filter again if not clear, and precipitate the 
phosphoric acid with magnesia mixture in the usual man- 
ner (§ 61, a). 

In the filtrate from the precipitated stannic oxide and 
phosphate, etc., determine the bases, as directed in A, C, 
and D, except that, since the precipitate by sodic acetate 
in A contains no phosphoric acid, the difference between 
the total weight of the precipitate by ammonia, and the 
weight of the ferric oxide, as determined by potassic per- 
manganate, gives the alumina. 

The method is not applicable in the jn-esence of hydro- 
chloric acid or chlorides. 

C. Precipitation of raanganiG hlnoxlde, MnO^^ in the 
filtrate from the precipitate hy sodic acetate in A. 

Heat this filtrate, which should he free from aminonic 
salts, and tolerably concentrated, to 50 or 60° C, and con- 
duct chlorine gas through it until it is saturated, or as long 
as any precipitate is formed ; filter out the precipitate, add 
more sodic acetate to the filtrate, pass chlorine through 
again, and add this second precipitate to the first, if any 
is obtained. Wash the precipitated manganic hydrate 
first by decantation and then on the filter, dry this, sepa- 
rate the precipitate from it as completely as possible, burn 
it and dissolve the ash and the precipitate in concentrated 



§ 93. QUANTITATIVE METHODS. 157 

liydrocliloric acid, remove any great excess of acid by 
evaporation, and precipitate the solution with sodic car- 
bonate. (§ 53.) 

Heat the filtrate from the precipitate by chlorine as long 
as any odor of the gas is perceived. 

D. Precipitation of lime, CaO, and magyiesia^ ^^gO^ 
in the filtrate from the precipitate hy sodic acetate (A) or 
hy chlorine (C). Neutralize the solution with ammonia if 
it is acid, and proceed as directed in § 50 h to precipitate 
lime with amnionic oxalate, and magnesia with hydrlc 
disodic phosj^hate. 

E. Separation and determination of sulphuric acid 
{anhydride)^ SO^. Precipitate the acid with baric chlo- 
ride in the slightest possible excess, and preserve the 
washings with water alone, while those Avith cupric acetate 
may be thrown away. (§ 59.) 

JF] Estimation of phosphoric acid {anhydride)^ P^0,_^^ 
in the filtrate from the precipitate by baric chloride. 

Add ammonia in slight excess only, if much iron or 
aluminum is present, otherwise a mixture of ammonia and 
amnionic carbonate, as long as a precipitate is formed, 
digest the mixture a considerable time until the free am- 
monia is expelled, wash the precipitate well, dissolve it, 
without drying it, in nitric acid, and eliminate P^O^ with 
amnionic molybdate. (§ 61. b.) 

G. Elimination of the alkaline metals as chlorides. 

(1.) Precipitate SO3 by the slightest possible excess of 
baric chloride, if this has not already been done ; evajjo- 
rate the mixture on the water-bath until most of the free 
acid has been removed, add pure milJc of lime in slight 
excess, digest some time on the water-bath, and filter out 
the precipitated ^efi, AIO3 MgO, and, SO3 and P,0,. 
Wash the precipitate as long as the washings make argentic 
nitrate turbid, precipitate the excess of lime in the concen- 
trated filtrate and washings, by amnionic carbonate con- 



158 § 93. SPECIxVL METHODS OP ANALYSIS. 

taining excess of ammonia, let the precipitate settle, filter, 
evaporate to dryness, and ignite ; dissolve the residue iu 
water, and precipitate again with ammonia and ammonic 
carbonate, filter, evaporate to dryness, and ignite;. and re- 
peat this operation as long as these reagents cause any 
turbidity ; finally, ignite gently, weigh the alkaline chlo- 
rides thus obtained, and determine potassium and sodium 
in the mixture by the indirect process (§ 46 c?), or, if greater 
accuracy is desired, precipitate potassium with platinic 
chloride (§ 46 ^). 

(2.) Precipitate the SO3 in the boiling solution with 
baric chloride in slightest possible excess, if this has not 
already been done, evaporate the mixture on the water- 
bath until most of the free acid is removed, add some wa- 
ter and then ammonia and ammonic carbonate as long as 
a precipitate is formed, and finally a little ammonic oxa- 
late, digest on the water-bath, filter, and wash the contents 
of the filter carefully. Evaporate the filtrate and wash- 
ings to dryness (§ 37), ignite the residue to expel ammo- 
niacal salts, weigh roughly, and add a quantity of a con- 
centrated solution of pure oxalic acid thixt contains enough 
of the acid to mahe quadroxalate with an amount of po- 
tassa equivalent to all the bases present, evaporate to dry- 
ness, and ignite again. By this process, magnesia and 
traces of lime, baryta, ferric oxide, etc., that may possibly 
be present, are rendered insoluble in water. Treat the ig- 
nited residue with a small quantity of boiling water, throw 
it on a filter, wash it with several small portions of boiling 
water, as long as anything is dissolved, add hydrochloric 
acid in slight excess to the filtrate and washings, evaporate 
to dryness, and ignite the residue of alkaline chlorides 
gently, weigh, and determine potassium and sodium by 
the indirect process (§ 46 c7), or with j^latinic chloride 
(§46 6). 

If, when these chlorides are dissolved in water, a clear 
solution is not obtained, or if the sohition has a basic re- 



§ 93. QUANTITATIVE METHODS. 159 

action, it should be evaporated to dryness and the residue 
treated with oxalic acid again. 

(3.) According to Stohmann {Fi'esenius's Zeitschrift, 5, 
306), potassium may be separated out at once by platinic 
cldoride from a solution containing only alkalies and alka- 
line earths. 

Having precipitated the sulphuric acid completely as 
above in the boiling solution of about 10 grins, of the 
substance, filter out the precipitate if the quantity of it is 
large ; if but small, let it remain in the liquid ; dilute the 
liquid, when cool, to 1000 c.c. and mix the Avhole thor- 
oughly together. To 100 c.c. of the clear solution add an 
amount of platinic chloride containing about 2 grms. of 
the metal, evaporate the mixture nearly to dryness, and 
proceed as directed for the separation of potassium and 
sodium by platinic chloride (§ 46 h). The method is based 
upon the fact that the double chlorides of calcium, barium, 
and magnesium, and platinum, are soluble in water and 
alcohol, as well as the double chloride of sodium and 
platinum. 

H. Separation of phosphoric acid alone. 

(li) Eva]3orate the liydrochloric acid solution, contain- 
ing no great excess of iron over the phosphoric acid, to 
dryness on the water-bath, to eliminate silica, moisten the 
perfectly dried residue with about 3 c.c. of concentrated 
hydrochloric acid, and, after a while, add about 10 c.c. of 
concentrated nitric acid (Sp. Gr. = 1.2) for every 0.15 
grm. of phosphoric acid supposed to be present, dilute 
with water, filter if necessary, and wash the residue of in- 
soluble silica; evaporate the filtrate and washings nearly 
to dryness, dissolve the residue in about half as much 
concentrated nitric acid as was added before, and proceed 
to precipitate phosphoric acid with amnionic molybdate 
(§ 61 l^. {Fresenius's Zeitschrift, 4, 404.) 

(2.) To the solution of the phosphate add ferric chloride 
in slight excess over the phosphoric acid, if there is not 



160 § 93. SPECIAL METHODS OF ANALYSIS. 

already enough alumina and ferric oxide present, so that, 
when the solution is nearly neutralized with sodic hydrate, 
heated to boiling and precij^itated with sodic acetate in 
excess, the filtrate gives no reaction for phosphoric acid. 

Nearly neutralize the solution with sodic hydrate or 
carbonate, heat to boiling, and add sodic acetate in excess, 
filter the mixture while hot, wash with boiling water con- 
taining a little amnionic acetate, dissolve, without igniting, 
in dilute hydrochloric acid, wash the filter out carefully, 
dilute the solution moderately, add rather a large quantity 
of citric acid, and then an excess of ammonia ; if enough 
citric acid is present, the solution remains clear. Finally, 
add magnesia mixture to the solution, and precipitate 
phosphoric acid in the usual manner. (§ 61 a.) 

The solution should not contain too large an excess c^f 
hydrochloric acid, and a great excess of citric acid must be 
avoided also. The method gives the best results when the 
proportion of phosphoric acid is large, as compared with 
the alumina and ferric oxide ; if these oxides are jDresent 
in large quantity, it may be necessary to re-dissolve the 
precipitate by magnesia mixture in hydrochloric acid, add 
citric acid, and re-precipitate the phosphoric acid by am- 
monia and a little magnesia mixture. 

(3.) In solutions containing a great excess of ferric oxide, 
it is better to reduce a portion of this, at least, to ferrous 
oxide before precipitation with sodic acetate. 

Heat the acid solution to boiling, remove the lamp, add 
a solution of sodic sulphite until the liquid is quite color- 
less, and sodic carbonate produces a white precipitate ; 
then boil the mixture as long as any odor of sulphurous 
acid is evolved, nearly saturate the acid with sodic carbon- 
ate, add a few drops of chlorine water, then sodic acetate 
in excess, and finally more chlorine w^ater drop by drop, 
until the liquid is reddish, and boil ; the precipitate con- 
tains all the alumina and phosphoric acid, mixed with but 
little ferric oxide ; filter it out quickly, wash it with a lit- 



§ 94. QUANTITATIVE METHODS. 161 

tie hot water, and dissolve it, without ignition, either in 
nitric acid and eliminate phosphoric acid with the aid of 
amnionic molybdate (§ 61, b), or in hydrochloric acid and 
precipitate the phosphoric acid with magnesia mixture in 
the presence of citric acid, as above. 

(4.) If there is a large proportion of phosphoric acid in 
the substance, and comparatively little ferric oxide and 
alumina, the nitric acid solution, obtained as in 1, may be 
treated with metallic tin, as described in £. 

94. Schemes for the quantitative sejyaration o/JC, JVa., 
Oa., 3Ic/., M., Al, Mn., P^O^, and jSO^. 

The j^urpose of these schemes is, to present a birds- 
eye view of the various courses to be followed for the 
separation of the bases and acids given in this list. 

For the details of the manipulation the analyst should 
always follow up the references given in the schemes and 
in § 93, unless he is perfectly familiar with these details, 
and knows them, as it were, by heart. 

The capital letters in the schemes refer to paragraphs 
in § 93, the small letters to other parts of the schemes 
themselves. 



162 



94. 



SPECIAL METHODS OF ANALYSIS. 



PUOSPHORIC ACID IS OK IS NOT IN EXCESS OVEli THE ALUMINA. AND 
FEKRIC OXIDE. 

Divide tlic filtrate from the silica in three parts, a, b, and c. 



1. Precipitate SO3 
witbBaCl, filter. (E.) 

2. Precipitate P2O5 
tog-ether with Fe,Ca, 
etc., with NH4HO,or 
NH4HO and (NH4)a 
CO3, filter. (F.) 

3. Eliminate K. and 
Na. as chlorides. 



b. I c. 

1. First add FcoClc inj 1. First add an accu- 
sliu;ht excess over tlie Ps-iratelv titrated solution 
O5 it AI2O3 and Fe^Og are|of FcoCIe in proper 
not already present injquantity (see A, 3) if 
excess (see A, 1); then AI2O3 and Fe.jOg are not 



by treat- 
ment with 

milk of 
lime, NH4 
HO and 
(NH4)-2- 
CO3, filtra- 
tion, evap 
oration to 
dryness, 
ignition 
G,l. 



ft- 

by evapo 
ration to 
dryness, 
ignition, 
addition 
of oxalic 

acid I igni 

tion, solu- 
tion in 

water, fil- 
tration, 

and 

ignition. 

G, 2. 



eliminate the acid, 



a. I /?. 

by addition by addition 
of NH4HO I of NaHO 
in slijh 
cess 



already present in ex- 
cess over the P2O5; then 
add Na2C03 until nearly 
neutral, and precipitate 
Fe,Al,P,05 with NaCs 



n shjht ex- until nearly ^352 dissolve precipi 
^ess, diges- neutral pre- t^te in HCl, divide ii 
tion, filtra- eipitation 1^^^^^^ precipitate one 



tion, solu 
tion of pre 
cipitate in 
HNO3 and 
precipita- 
tion of P2O3 
with(NH4)o- 
M0O3. 

11, 1. 



m 

... ^T ^ ^^, precipitate 

t7^A / -" half with NII4HO, filter 
II3U0 (or use igiiite,and weigh AJ,F_e, 



of NH4HO 

and NH4C0- 
H3O2 if alka- 
lies are to 
be determ- 
ined in fil- 
trate); dis- 
solve pre- 
cipitate in 
HCl, precip- 
itate P2O5 
Avith mag- 
nesia mix- 
ture and 
citric acid. 
H, 2. 



2. Treat filtrate from 
precipitate by Nn4H0 m\{NHi).iC.Oi.) 



P2O5. Determine Fe in 
other half witli K2Mn2- 
Og, at once, or after pre 
eipitation Avith ]SiH4H0 
and solution in H0SO4. 
(A.) 

2. FlliST FlLTR. — 

{From theprcc. by NaC^- 
-H3O2). Concentrate and 
precipitate Mu by CI. 
(C.) 

3. Second Filth.— 
{From the i^rec. by CI.) 
Concentrate,precipitate 
Cawith(NH4)oC204 (D). 

4. Third Filtr.— 
{From the prec. by 

Concen- 



a or NH4C2H3O2 in /? as!trate and precipitate 
under a, if it is desired ^^^i^'- with Na^H, PO4 
to repeat the determiua-j(I^)- 
tion of alkalies. 1 



II. 

A LARGE EXCESS OF BOTH ALUMINA AND FERRIC OXIDE IS PRESENT. 

Divide the filtrate from the silica in three parts, a, b, and c. 



1. Precipitate SO3 with Ba- 
Cl and filter. (E.) 

2. Eliminate K and Na as 
chlorides. See Scheme I, 
a, 3. 



Treat this 
portion as 
directed iu 
Scheme I 
under c. 



Reduce the ferric to fer- 
rous oxide with sodic sul- 
phite (H,3), precipitate all 
Al and P2O5 together with 
little Fe, and eliminate P0O5 
as under a or /?, Scheme ]', b. 



94. QUANTITATIVE METHODS. 



163 



III. 

NO ALUMINA IS PRESENT, AND rnOSPHORIC ACID IS IN EXCESS OVEIi 
THE IRON. 

Divide tlic filtrate from tli3 silica in two parts, a and b. 



Determine 

SO3, Fo05,K, 

and Na, as 

nndera, 

Scheme I. 



1. Add an accuratel}^ titrated solution of FcoCls, nearly 
neutralize the solution with NaoCOs, precipitate Fe and 
P2O5 with NaCoIIgOa (A); dissolve the precipitate in HCl, 
divide solution in two equal portions, a and jj. 



Determine Fe with per- 
mauyanate (A.) 



2 [i. 
Determine P0O5 with (NH4)2- 
M0O3 (H, 1) or citric acid and 
ma<;-nesia mixture (H, 3). 



3. Determine Mn, Ca, and Ms,^, in the filtrate from tlie 
precipitate by NaCoHaOa, as iu 2, 3, and 4, under c, 
Scheme I. 



IV. 

NO ALL'MINA OR MANGANESE IS PRESENT, AND PHOSPHORIC ACID IS IN 
EXCESS OVER THE IRON. 

Proceed as in III, except that the elimination of mang-ancse by chlorine 
may be omitted. 



TO DETERMINE ALL WITHOUT DIVIDING THE SOLUTION. 

1. To the filtrate from the silica add the titrated solution of ferric 
chloride, if necessary, (see § 93, A, 2), nearly neutralize the solution with 
(NH4)oC03, precipitate Fe, Al, and P0O5, with NH4C0H3O2, dissolve the 
precipitate in HCl, and divide the solution in two equal portions ; pre- 
cipitate one portion with NH4HO, and get total Al, Fe, and P0O5; heat 
the ignited residue in a mixture of 8 parts of concentrated sulphuric 
acid and 3 parts of Avater, add water, and determine Fe in this solution 
with potassic permanganate (A) ; eliminate P2O5 in the other portion of 
the solution, with the aid of amnionic molybdate, or magnesia mixture 
in the presence of citric acid. (IT.) 

3. First Filtrate. {From the precijx by NIIiC^HsO-i.) Evaporate 
to dryness and ignite the residue until ammonic salts are completely ex- 
pelled; dissolve in water acidified with HCl, nearly neutralize the solu- 
tion with NasCOa, add NaCsHgO^/and precipitate Mu by CI. (C.) 

3. Second Filtrate. {From iJie 2^1'ecipitafeb]/ CI.) After removing 
excess of CI by heat, precipitate Ca with (NIl4)oCo04. (D.) 

4. Third Filtrate. {From ihejirecip. by {NllijnC^Oi). Precipitate 
SO3 with BaCl. (E.) 



164 § 94. SPECIAL METHODS OF AX^iLYSIS. 

5. Fourth Filtrate. {From the x>recip. hy Bad.) Kemove excess 
of Ba with (NH4)2 CO3, evaporate filtrate to dryness, ignite, treat with 
H2C2O4, (see G, 2), ignite, exhaust with water, and treat tliis solution for 
the estimation of tlie alkalies, as directed for the treatment of the cor- 
responding solution in G, 2. 

6. Dissolve the residue that has been exhausted by water as above, in di- 
lute HCl, filter if necessary, and precii3itate Mg in the filtrate with NaaH 
PO4 (§ 50, a). 

VI. 

TO DETERMINE ALL EXCEPT MANGANESE, WITHOUT DIVIDING THE 
SOLUTION. 

Proceed as under V, except that the evaporation to dryness, ignition, and 
treatment with CI for the estimation of Mn, are to be omitted. 

VII. 

TO DETERMINE ALL EXCEPT MANGANESE AND PHOSPHORIC ACID, WITH- 
OUT DIVIDING THE SOLUTION. ' 

Proceed as under VI, except that no FcoCIg need be added, and that one 

portion of the solution of the jDrecipitate by NH4C2H3O2 is to be used for 

the estimation of the sura of the Fe and Al only, and the other portion 

for the determination of Fe. (A.) 

VIII. 

TO DETERMINE ALL EXCEPT ALUMINIUM AND MANGANESE "WITHOUT 
DIVIDING THE SOLUTION. 

Proceed as under VI, except that one portion of the solution of the pre- 
cipitate by NH4C2H3O2 is to be used for the estimation of Fe, and the 
other for that of P2O5. (A, H.) 

IX. 

DETERMINATION Or ALL, AND ELIMINATION OF PHOSPHORIC ACID BY 
THE TIN PROCESS. 

Divide the filtrate from the silica in two parts, a and b. 



a. 

1. Precipitate 
SO3 with BaCl, 
and filter. (E.) 

2. Eliminate K 
and Na as chlo- 

lides. (8ee 
Scheme I, a, 3.) 



b. 

1. Treat the concentrated nitric-acid solution with 
Sn, this precipitate by NIl4nS, and thesolution so ob- 
tained with magnesia mixture (B). 

2. First Filtr.' (From the preeip. by Sn.) Pi-ecipi- 
tate Fe and Al by NaHO and NaC2H302, dissolve the 
precipitate in HCl, divide solution in two equal parts, 
precipitate one part by NH4HO to get total Al and Fe, 
and determine Fe in the other paii (A). 

3. Second Filtr. (From the iirecip. by NaC2H302.) 
Treat this for the estimation of Mn, Ca, and Mg, as in 
Scheme I, under c, 2, 3 and 4. 



§ 95. SOILS. 165 

X. 

TO DETERMINE ALL EXCEPT MANGANESE, WITHOUT DIVIDING THE 
SOLUTION. 

a. Eliminate P2O5 from the filtrate from the silica, bv means of Sn 
(VIII, b). 

b. First Filtr. (From the preeip. by Sn.) Precipitate Al and Fe with 
NH4HO and NH4C2H3O2, and treat this precipitate as directed for the 
treatment of the corresponding- one by NaC2H302 iu VIII, b. 

c. Secoud Filtr. Treat this, for the estimation of Ca, SO3, K, Na, and 
M"-, as directed iu Scheme V, 3, 4, 5 and 6. 



CHAPTER Y. 

ANALYSIS OF SOILS AND EOCKS. 
L 

SOILS. 

95i The following general method of analyzing soils, 
by Emil Wolff, was approved at the annual meeting of 
German Agricultural Chemists in Gottingen, in 1864, 
and is given in full in his work on agricultural analysis, 
referred to in the preface. 

In his introductory remarks. Prof. Wolff Avrites : " Of 
course it is not essential that the experienced chemist 
should follow strictly all the methods for the separation 
and quantitative estimation of particular components of 
the soil, that are given here as guides for the beginner 
in chemical analysis, and are used by me ; those methods 
may be modified in many cases without impairing the 
accuracy of the analytical work. But it is necessary 
that all chemists who undertake accurate analyses of 
soils should agree to follow the same course in regard to 



166 § 96. ANALYSIS OF SOILS AND HOCKS. 

certain important points, in order that the results ob- 
tained by different workers may be comparable with 
each other, or possess any lasting practical, or scientific 
value. 

" Such essential points, concerning which agricultural 
chemists should aim to agree, are, the manner in which 
the sample of the soil is to be taken from the field, the 
preparation of the same, and the quantity to be taken 
for analysis, the manner of performing the mechanical 
silt (Schlamm) analysis, the methods of determining the 
coeflicients of absorption of the more important elements 
of plant-food, and, above all, the preparation of the solu- 
tions or extracts of the soil that are to be subjected to 
chemical analysis." 

He says also in another place : 

" Although I recognize the need of a large number of 
full and complete analyses of soils, and of improving or 
amplifying some of the methods given here, in order to 
perfect our scientific knowledge of the soil, yet an abridg- 
ment of the following course will usually answer for all 
practical purjDOses ; for such an abridged course, it will be 
sufficient, for example, to examine only that part of the soil 
that is soluble in cold or hot concentrated hydrochloric 
acid, with perhaps the addition of a mechanical analysis ; 
but even in this case, the previous preparation of the soil 
and of the solutions to be analyzed should be made in 
accordance with the directions given below, at least until 
other methods become as generally approved and adoj^ted.'* 

PREPARATION OF THE SAMPLE FOR ANALYSIS. 

96. Make an excavation in the soil 30-50 cm. deep, or 
through to the subsoil, and 30-50 cm. square, with one 
side as nearly vertical as possible, and take a slice from 
this side of uniform thickness throughout, weighing 4-5 
kilos. The subsoil lies below the depth generally reach- 



96. PEEPAEATION OF THE SAMPLE FOR ANALYSIS. 167 

ed by the plough, and is usually readily distinguished 
from the upper soil by its physical characters, among 
which a lighter color is prominent, owing to the absence 
of humus. If this subsoil is to be examined, a sample 
of it should be taken out in the same manner as directed 
for the upper soil, to the depth of about 60 cm., and the 
depth of the cavity noted. 

The sample is taken, according to the object of the 
analysis, either 

r/, from one or from several spots in the field, in order 
to subject each sample to a separate analysis; or 

Z>, for an average representation of the soil of the whole 
field ; in this case, several portions of earth arc taken 
from points distributed in a regular manner over the 
field, all of which are most carefully mixed together, and 
4-6 kilos, of the mixture, free from any large stones, are 
preserved as the average sample. 

If the character of the soil varies materially in differ- 
ent parts of the field, samples from several spots should 
be analyzed separately. 

A small portion of the sample should be put at once in 
a well-stoppered bottle ; the remainder may be allowed 
to become air-dried, by exposing it in a thin layer, in 
summer, to the common temperature in the shade, or, in 
winter, to that of a warm room, or a moderately warm 
drying-chamber, heated to 30°-40° C. ; in either case it 
should be carefully protected from dust. 

At the time of taking the sample of the soil, obser- 
vations should be made in regard to the following points : 

a. The geognostic origin of the soil. 

b. The nature of the underlying strata, to the depth 
of 1-2 metres, if practicable. 

c. The meteorology of the locality — by consulting me- 
teorologieal records, if possible ; otherwise, by the general 
opinion of the neighborhood ; in this connection, the 



1G8 § 96. ANALYSIS OF SOILS AND KOCKS. 

height of the locality above the level of the sea should 
be noted also. 

d. The management and rotation of crops in previous 
years. 

e. The character of the customary manuring. 

f. The amount of the crops removed in the preceding 
year, and, if possible, the average amount of each of the 
more important crops yielded by the field. 

g. The practical judgment of neighboring farmers in 
regard to the field. 

Having taken the sample to the laboratory, separate 
the stones and larger pebbles from the finer parts by the 
hand, or by sifting with a very coarse sieve, and examine 
them with reference to their mineralogical character, 
weight and size, making note, in this last respect, of the 
number that are as large as the fist or larger, the num- 
ber as large as an (^^^.^ a walnut, hazel-nut, and pea, or 
give the percentage of each by weight. 

Pulverize the air-dried soil in a mortar with a wooden 
pestle, and separate the fine earth out by a sieve with 
meshes 3 mm. wide ; this sieve should have a tightly fit- 
ting cover of sheep-skin stretched over a hoop, and it 
should be covered in the same manner underneath, so 
that no dust can escape during the process of sifting. 

Wash the pebbles and vegetable fibres remaining on 
the sieve with water, dry and weigh the residue, and ex- 
amine the pebbles mineralogically ; the water with which 
this gravel was washed should be evaporated to dryness 
at a temperature not exceeding 50° C. towards the close 
of the evaporation, and the residue mixed with what 
passed through the dry sieve. 

This sifted fine earth is reserved for all the processes 
hereinafter described, and is kept in well-stoppered bot- 
tles, marked air-dried fine earth. 



§ 9T. SILT ANALYSISc 169 

SILT ANALYSIS. 

97. This air-dried fine earth may be separated, still 
further, into j^ortions of different degrees of fineness by 
a series of sieves, or, in a quicker and better manner, by 
tlie process of silt analysis. 

a. To perform this with Nobel's apparatus (fig. 6), 
weigh out 30 grms. of the air-dried soil, and boil it for a 
long time with water, until the lumps are completely 
broken up ; the operation may be facilitated by gentle 
trituration with a small pestle ; in the case of very sandy 
soils, it will be finished in half an hour, but for very 
heavy clay soils, two or three hours may be required. 

When this is completed throw the whole mixture of 
soil and water on a sieve with meshes 1 mm. wide, rinse 
the residue on the sieve well with water, dry it at 100° C, 
and weigh it ; that which passes through the sieve, and 
the washings, are reserved for the silt analysis proper. 

The water reservoir of Kobel's apparatus should hold 
about 10 litres, and the siphon tube that enters it should 
extend down just far enough to allow 9 litres of water, 
and no more, to flow out ; the other arm of the siphon 
should be CO cm. long, and should have just as large a 
bore as the tube of the funnel with which it is connect- 
ed. The relative capacities of the four silt funnels, Kos. 
1, 2, 3, and 4, are 1 : 8 : 26 : 64 ; together, they hold 5 
litres ; the mouth of the largest funnel where the water 
finally flows out of the apparatus should be provided 
with a tube drawn out to a point, that is filed off until 
the orifice is of such a size that, when all the funnels are 
filled with water, and the connection with the reservoir 
is made as above directed, 9 litres will flow through in 
exactly 40 minutes. 

A large flask or beaker must be provided to receive 
the water as it flows out of the largest funnel. 

The fine earth, that passed through the sieve with 
8 



170 



97. 



ANALYSIS OF SOILS AJq^D EOCKS. 



meshes 1 mm. wide, is stirred up witli water ; in case 
there is reason to suppose that funnel No. 2 will not hold 
all this mixture of soil and water, a part of the latter, 
holding only the finest particles in suspension, may be put 
in funnel No. 3 ; then pour the rest of the mixture, just 
after it has been well stirred, into the second funnel, 




Fig. 6. 
while any very coarse sand remaining in the beaker may 
be rinsed into the first funnel ; but it is better to put the 
whole in the second funnel, if possible. 

All the funnels are then filled with water, the connec- 
tions carefully made between them with gum tubing, and 
the siphon leading from the reservoir is filled and con- 
nected with the smallest funnel. As soon as 9 litres of 
water have passed through, the connection with the 
reservoir is closed by means of a clamp on the gum tube. 

The whole apparatus is then allowed to stand about 
five hours, until the solid matters in the funnels have 



§ 97. SILT ANALYSIS. 171 

settled to the bottom ; then draw off the clear supernat- 
ant liquid from each funnel with a siphon, and transfer 
each portion of the sediment to a separate evaporating 
dish, except that the contents of funnels 1 and 2 should be 
mixed together; dry each portion at 125° C, and weigh 
it. After this, ignite each one and weigh again, and 
thus determine the amount of organic matter in it. 

By this operation the soil is separated into at least five 
portions, of different degrees of fineness. 

1. The residue on the sieve. 

2. The contents of funnel ISTo. 2. 

3. " " " " No. 3. 

4. " " " " :N'o. 4. 

5. The sediment deposited from the water that flowed 
through the whole apparatus, and the still finer portions 
remaining suspended in the water even after several 
hours. These two may be separately determined, if it is 
desired, by collecting, drying, and weighing the sediment 
that is deposited after several hours, and then estimating 
the still finer portion that remains in suspension, together 
with the hygroscopic water of the soil, by the difference 
between the 30 grms. of soil taken originally, and the 
sum of these five residues; then on subtracting from 
this remainder the hygroscopic water, as determined in 
another portion of the soil, we have the weight of the 
sixth portion ; or, the fifth and sixth may be estimated 
together, in a similar manner, and without collecting the 
sediment deposited in the beaker. 

To clarify this liquid more speedily, A. Mtiller {Jour- 
nal fur Frcikt. Chemie^ 95,92; Frese7iius's Zeitschrift, 
5, 243) recommends the following process. Prepare a 
solution of an ammoniacal soap, with the aid of stearic 
acid, ammonia, and alcohol, add it to the turbid liquid 
until the mixture gives considerable foam when violently 
agitated, then acetic acid until the reaction of the liquid 
is decidedly acid, and stir or shake the whole vigorously; 



172 



97. a:n'alysis of soils and eocks. 



the fatty acid that is set free by the a-cetic acid envelopes 
the fine particles of earth, and the flocculent sediment 
can be filtered out without difficulty. The fatty acid 
may then be removed from the other solid matters, with 
which it is mixed, by ignition, or by treatment witli alco- 
hol, and the residue Avill represent the finest portion of 
the soil. 

h. The following method of silt analysis, by Dietrich 
{Fresenius' s Zeitschrift, 5, 296) is preferred by some to 
that described above ; the apparatus may be easily con- 
structed out of the ordinary stock of the laboratory. 

The water is caused to flow, under a constant pressure 
of 1 metre, through a series of four tubes of different 
sizes, and inclined to the horizon at different angles, as 
follows ; 



Number 

of 
the tube. 


Length. 


Diameter. 


Angle between its axis 

and a 

horizontal jylane. 


1 
2 
3 
4 


17 cm. 
34 " 
51 " 

68 " 


2.8 cm. 
4 

5.2 " 
6.4 " 


90° 
67.5" 

45° 
22.5° 



• Each tube is drawn out at one end so that a rubber 
tube can be attached to it, while the other end is closed 
with a rubber cork, through which a short glass tube 
passes ; each tube is connected with the next larger one 
by a rubber tube passing from the corked end of the 
former, which is at the same time the upper end, to the 
lower, tapering end of the latter, and the water flows 
from the upper end of one tube to the lower end of the 
next larger one. Each rubber tube is cut in the middle 
of its length, and the cut ends are connected together by 
a short glass tube ; each rubber tube also has a clamp on 
it, by means of which the flow of the water can be regu- 
lated. The 30 grms. of soil, prepared as for the silt 
analysis with Kubel's apparatus, are put in the first 



§ 98. , THE CHEMICAL ANALYSIS. 173 

tube, and the flow of the water through the apparatus is 
contmued until it comes away from the last tube tolera- 
bly clear. The remainder of the operation is conducted 
in the same manner as when using Nobel's apparatus. 

THE CHEMICAL ANALYSIS. 

98t The soil for tliis analysis should always be taken 
in its natural, air-dried condition, without previous igni- 
tion to expel the organic matter, since the ignition may 
at the same time alter very materially the effect of the 
agents employed for solution. 

a. Hyj^roscopic water and other volatile matter. — 

Determine the amount of water expelled at 100° C. from 
10 grms. of soil (§ 90), and then ignite the dried residue 
to determine water chemically combined or otherwise re- 
tained at 100° C, humus, and volatile mineral substances 
(§ 91) ; the ignited residue should be treated with am- 
monic carbonate, if a qualitative test reveals the presence 
of carbonic acid in the soil, and carbonic acid should be 
determined in the ash (§ 91, d). 

A. Miiller allows but little value to this estimation of 
water of hydrates in the soil, and organic matter, even 
when combined with the determination of carbonic acid 
both before and after ignition. 

h. Estimate carbonic acid in 5-10 grms. of soil, dried 
at 100° (§ 60, V), 

c. Determine the total nitrogen in 5-10 grms of soil, 
dried at 100°, by combustion with soda-lune (§ 85). 

A. Midler mixes the soil with about an equal quantity 
of caustic potash or soda, instead of with soda-lime, but 
fills the rest of the tube Avith soda-lime in the usual man- 
ner ; in this way he avoids the use of very long combus- 
tion-tubes. 

If much nitrate is present in the soil, and but little hu- 



174 § 99. ANALYSIS OF SOILS AND ROCKS. 

mus, it will be safer to add 0.2-0.4 gnu. of pure cane 
sugar to the sample in which' nitrogen is determined; 
otherwise some of the nitrogen may escape conversion 
into ammonia; a small pgrtion of the sugar should be 
ignited by itself with soda-lime, either to determine the 
amount of nitrogen it contains, or to be sure of its free- 
dom from that impurity. 

d. In order to determine the solubility of the various 
elements of plant-food in the soil, it is necessary to treat 
it successively with diiferent solvents, and with these of 
various degrees of strength ; in order that the results ob- 
tained by different chemists may be compared with each 
other, it is absolutely essential that these solvents should 
be applied in the same order and in the same manner. 

A convenient and useful order is the following : 

1. Cold, distilled water, ^|^ saturated with carbonic 
acid. 

2. Cold concentrated hydrochloric acid (Sp. Gr. = 1.15), 

3. Boiling concentrated hydrochloric acid of the same 
strength. 

4. Hot concentrated sulphuric acid. 

5. Hydrofluoric acid. 

The solutions obtained by the treatment of the soil 
with these agents in succession will be found to differ 
very much in their composition, and to yield data for 
very interesting deductions in regard to its natural fer- 
tility. 

Unless, however, a very complete analysis is desired, 
but one of these solutions, viz., that in cold concentrated 
hydrochloric acid, need be examined quantitatively ; next 
to this, the solution in hot hydrochloric acid is of great- 
est importance ; we shall, therefore, consider the treat- 
ment of these first of all. 

Solution ill (old (onceatrated Hydrochloric Acid. 

99. Put 450 grms. of air-dried soil in a large, glass- 



§ 99. THE CHEMICAL ANALYSIS. 175 

stoppered bottle, and pour over it 1500 c.c. of pure con- 
centrated hydrochloric acid (Sp. Gr. = 1.15), and shake 
the mixture frequently during a digestion of 48 hours, at 
the common temperature of the working-room ; then let 
it stand until 1000 c.c. of at least a tolerably clear liquid 
can be poured off or drawn off with a siphon ; this quan- 
tity of the solution represents ^\^of 450 grms., or 300 
grms. of the soil taken for the analysis ; dilute the liquid 
with its volume of water, and filter it. 

If the soil contains a very large proportion of calcic 
carbonate, the cold acid solution may be filtered off after 
dilution with its volume of water, and the whole quan- 
tity used for the analysis, representing the whole of the 
soil taken ; in this case, wash the insoluble residue care- 
fully first with cold and then with hot water, dry it at 
100° C, and weigh, to deteimine the proportion of the 
soil insoluble in cold acid ; 5-10 grms. of this may be 
ignited, to determine the organic matter in the insolu- 
ble portion ; then reserve the rest for treatment with so- 
dic carbonate, to determine soluble silica, and with hot 
concentrated acid. 

Evaporate the solution to dryness with the addition of 
a few drops of concentrated nitric acid towards the close 
of the evaporation, to oxidize ferrous oxide and organic 
matters, and eliminate silica (§ 58, «, 1). 

Dilute the filtrate from the silica to 1000 c.c, and 
analyze it according to Scheme II., § 94, taking 400 c.c. 
for a, 200 for b, and 400 for c. 

In b, a slight insoluble residue often remains, on dis- 
solving the precipitate by sodic acetate in hydrochloric 
acid ; in this case, dry the residue, ignite it and the filter, 
digest the ash a long time with concentrated hydrochloric 
acid, filter if necessary, and add the filtrate to the re- 
mainder of the solution of the precipitate by sodic ace- 
tate in hydrochloric acid, ignite and weigh the insoluble 
residue, if there is any, and add it to the silicic acid. 



176 § 99. AI^ALYSIS OF SOILS AND KOCKS. 

If the soil is very rich in organic matter, it will be bet- 
ter to treat 500 c.c. of the solution Avitli sodic carbonate 
and potassic nitrate, or Avith chlorine, as directed in 
g 93, A, and use "1^ of the solution finally obtained for 5, 
omitting, of course, the determination of the alkalies 
in this portion of the solution unless the oxidation was 
eifected with chlorine, and '1^ for c. 

Sometimes, however, when there is not a very large 
proportion of organic matter present, and the above 
treatment for oxidation is not followed, traces of organic 
matter are contained in the solution of ferric oxide ob- 
tained in 5, for estimation with permanganate; Avherc 
great accuracy is required therefore, it would be well, 
after having titrated the ferric solution once, to reconvert 
the ferric oxide into ferrous, with zinc or sulphurous 
acid, titrate the solution again, and to repeat this until 
a constant result is obtained. The same mode of pro- 
cedure should be followed, also, in estimating the strength^ 
of the permanganic solution. 

In accurate soil analyses, the phosphoric acid should be 
estimated twice. 

In a complete soil analysis, it is desirable to determine 
the siliciG add, w^hich, after treatment of tlie soil with 
cold concentrated hydrochloric acid, is soluble in a con- 
centrated solution of sodic carbonate. 

For this purpose, take 5-10 grms. of the residue that 
was insoluble in the acid, in case of a soil rich in carbon- 
ates ; or, digest 25 grms. of the air-dried soil with three 
times the quantity of cold concentrated acid, 48 hours in 
the cold, filter, and wash the contents of the filter pcrse- 
veringly, first with cold and afterwards with hot water, 
and use this residue. 

Boil this insoluble substance and also an equal amount 
of the original air-dried soil, with sodic carbonate, in the 
manner described for the separation of sand and silica 
(§ 58, <7, 2). The difierence between the amounts of 



§ 100. THE (ni:MICAL ANALYSIS. 177 

silicic acid dissolved in the two cases furnishes a means 
of estimating the extent of the action of the cold acid on 
the silicates in the soil. 
Treatment of the Soil with Carbonated Water. 

100. To determine only the total ^quantity of organic 
and inorganic matters in the soil, soluble in water con- 
taining carbonic acid in solution, Avithout reference to the 
composition of the dissolved substances, put 500 grms. 
of air-dried soil in a flask that can be well stoppered, and 
pour over it as much carbonated water as Avill make, to- 
gether with the hygroscopic water in the soil, 2000 c.c. 
The water should be ^1^ saturated with carbonic acid, by 
saturating 500 c.c. at the common temperature and press- 
ure, and mixing this with 1500 c.c. of pure vrater. When 
thus prepared, the water is more nearly like that in the 
soil, whose action we wish to imitate. 

Leave the soil and water in contact with each other 
three days, with frequent agitation, then pour off 1000 
c.c. of as clear a liquid as possible, representing 250 grms. 
of soil, and filter through a double filter, while keeping 
the funnel well covered with a glass plate. Evaporate 
the clear filtrate to dryness at a temperature below boil- 
ing, dry the residue at 125° C, weigh, ignite, and after 
treatment several times with amnionic carbonate and 
gentle ignition, weigh again. The difference between the 
two weights gives the amount of organic matter dissolved 
by the carbonated water. 

The carbonic acid is determined in the ignited residue, 
as in § 60. 

If a detailed ch(Tmical examination of the solution in 
carbonated water is to be made, at least 1500 grms. of 
soil must be taken instead of 500, and the water in the 
same proportion. After three days, pour oflf 4000 c.c. of 
the clear supernatant liquid, representing two-thirds of 
the soil, let it stand 24 hours in well-closed and full 
bottles, filter as directed above, and without disturbing 



178 § 100. ANALYSIS OF SOILS AND KOCKS. 

the sediment at the bottom of the bottles. If a clear 
filtrate is not obtained in this way, it must be evaporated 
down to 400 or 500 c.c., just barely supersaturated with 
hydrochloric acid while still hot, and then filtered again. 

Evaporate the solution to dryness, with the addition 
of a few drops of nitric acid towards the close of the 
evaporation, to peroxidize the iron and destroy organic 
matter, and eliminate silicic acid. (§ 58, a, 1.) 

Treat the filtrate from the silica as in Scheme L, § 94. 
Alumina, ferric oxide, and phosphoric acid, are usually 
present, however, in such small quantities in this solution, 
that it is hardly worth while to determine at least the 
first two. 

Interesting results may be obtained by the successive 
treatment of the same portion of soil Avith carbonated 
water, and a chemical examination of each solution ; the 
proportion may thus be learned in which the more im- 
portant elements of plant-food are taken up by the suc- 
cessive aqueous extracts, and data are obtained for esti- 
mating, not only the general richness of the soil in 
valuable elements of plant-food, such as phosphoric acid 
and potassa, but also the relation between the immediate 
fertility of the soil and the durability of its fruitfulness. 

A very great decrease in the amount of the elements 
of plant-food in the second and third extracts, as com- 
pared with the first, would indicate that the fertility of 
the soil would be very much lessened in a single season. 
If, on the contrary, there is but little diminution observ- 
ed even in the fifth extract, the jjower of the soil to 
produce crops will probably remain about the same, year 
after year, for a long time. 

To obtain these successive extracts, replace the 4000 
c.c. that were poured off* for the first extract, by an equal 
quantity of fresh Avater \ saturated with carbonic acid as 
before, let stand three days with frequent shaking, pour 



§ 101. THE CHEMICAL ANALYSIS. 179 

off 4000 c.c. again, and repeat this operation for the third 
and fourth time, or even more, as may be desired. 

Ulbricht found, that after the third or fourth extract, 
the amount dissolved, at least by distilled water free from 
carbonic acid, remained nearly constant, and that the 
composition of one of these last extracts would furnish 
the means for estimating the lasting fertility of the soil. 

It will usually answer to examine quantitatively the 
first, third, fifth, and seventh extracts by carbonated 
water. 

Interesting results may be obtained also by treating 
the soil in the manner above directed with water contain- 
ing 0.5 gnn. of amnionic chloride in the litre, in addition 
to the usual charge of carbonic acid. 

Treatment of the Soil with Hot Concentrated 
Hydrochloric Acid. 

101. If the soil contained a very large proportion of 
calcic carbonate, the residue insoluble in cold acid may 
be treated with hot acid ; otherwise the separation of the 
insoluble from the soluble part by filtration is too diffi- 
cult, and it is better to begin with a fresh portion of soil. 
Pour 300 c.c. of concentrated acid over 150 grms. of the 
air-dried soil, or over the Avhole of the residue insoluble 
in cold acid in case carbonates were present in large 
quantity, in a large flask, add a few drops of nitric acid 
to oxidize slimy matters that might obstruct the filter, 
heat to boiling with constant agitation, and continue to 
boil gently for exactly an hour ; dilute the solution with 
twice its volume of water, and, after letting the mixture 
stand quietly for a short time, decant the liquid into a 
filter that is double at the bottom ; treat the insoluble 
residue in the flask at least three times with boiling Ava- 
ter, filter the liquid each time, and finally bring the resi- 
due itself on the filter, and wash it thoroughly Avith boil- 
ing water. 

Evaporate the solution and washings to dryness, with 



180 § 102. ANALYSIS OF SOILS AND EOCKS. 

the addition of a few drops of nitric acid towards the 
close of the evaporation, to destroy organic matter and 
oxidize ferrous salts, and eliminate silica. (§ 58, cr, 1.) 

Examine the filtrate from the silica, which is to be 
made up to 1000 c.c. and well mixed, according to 
Scheme II., § 94. 

Or, in order to have a larger quantity of solution for 
the determination of phosphoric and sulphuric acids, the 
analysis may be performed by Scheme I., in which a and 
h may be united, and the sulphuric acid determined as 
usual, while half the filtrate from the precipitate by 
ammonia for phosphoric acid will answer for the determi- 
nation of the alkalies. 

Examination of tlie Residue Insoluble In Hot Hydro- 
chloric Acid, 

102. Dry it, and remove it from the filter as completely 
as possible, burn the latter, and weigh ash and residue, 
and separate the carefully prepared mixture of the two 
into three accurately weighed portions of 10 grms. (a), 
10-15 grms. (^), and 15-20 grms. (c). 

a. Ignite this portion, to determine the amount of min- 
eral matter insoluble in the hot acid. 

h. In this portion determine the silica soluble in car- 
bonated alkali. (§ 58, a, 2.) 

c. Pour five times its weight of concentrated sulj^huric 
acid over this portion, heat until the excess of acid is 
removed, and the residue forms a light, dry powder ; the 
evaporation of the acid should be performed slowly and 
with constant stirring, and should require from six to 
eight hours. Moisten the residue freely with concentrat- 
ed hydrochloric acid, remove this acid by long heating in 
the water-bath, boil the residue repeatedly with water to 
which a little hydrochloric acid has been added, filter, and 
wash the insoluble residue carefully. 

Examine the solutions and washings, after concentra- 
tion, according to Scheme VII., § 94. 



§ 103. THE CHEMICAL ANALYSIS. 



181 



The amount of lime is usually small. Wolff directs 
that the filtrate from the precipitate of calcic oxalate be 
evaporated to dryness, the residue ignited gently in a 
platinum dish, to expel ammoniacal salts, dissolved in di- 
lute acid, and any silicic acid that may appear as an in- 
soluble residue be filtered out; then add ammonia in 
slight excess to the filtrate, filter out any flocculent pre- 
cipitate of alumina that may also appear, and finally de- 
termine sulphuric acid with baric chloride. 

This treatment of the soil with sulphuric acid serves 
to determine the amount of clay in it, and \Yolff has 
found, by repeated trials, that the clay is completely 
decomposed if the operation is carefully performed. He 
gives importance to the determination, for it furnishes data 
for controlling the results obtained by the silt analysis, 
and because it gives valuable information in regard to 
the degree of insolubility of the other constituents of the 
soil, and particularly the alkalies. 

The process is a good connecting link between the 
treatment with hydrochloric acid on the one hand and 
hydrofluoric acid on the other. 

Examination of the Resicliie Indecomposed by Sul- 
phuric Acid. 

103. a. Dry this residue at 100°, burn the filter by it- 
self, and weigh the ash and residue ; mix them well to- 
gether, and, in half of the mixture, determine silica solu- 
ble in alkaline carbonates. (§ 58, a, 2.) The silicic acid 
thus found, together with the small quantity in the 
hydrochloric and sulphuric acid solutions, gives, in con- 
nection with the alumina found in the same solutions, 
an approximate estimate of the pure anhydrous clay in 
the soil. This amount of silicic acid is, in general, too 
large in proportion to that of the alumina, for a part of 
it was combined with ferric oxide, lime, etc. 

The clay that is decomposed by the sulphuric acid 



182 § 103. ANALYSIS OF SOILS AND ROCKS. 

alone is very nearly pure, while it is that which is dissolved 
by the hydrochloric acid that contains too much silica. 

Ignite the other half of the residue, to determine the 
amount of mineral matters insoluble after treatment with 
sulphuric acid. 

Pulverize the ignited mass very finely in an agate 
mortar, separate the finer from the coarser portions by 
levigation (§ 36) with distilled water, pulverize the coarse 
part again, and repeat the levigation ; when in this way 
the whole is reduced to the finest possible powder, evap- 
orate the water to dryness with the matters in suspension 
in it, weigh out 3-4 grms. of the well-dried residue, and 
treat it with hydrofluoric acid or amnionic fluoride 
(§58,e). 

Examine the solution thus obtained according to Scheme 
VII., § 94. The determination of ferric oxide will, how- 
ever, be necessary only when the precipitate by ammonia 
is yellowish or reddish. 

If, as is usually the case, the solution is found to con- 
tain only traces of lime and magnesia, the amount of 
feldspathic minerals and of pure quartz sand in this in- 
soluble part of the soil can be estimated from the amount 
of alkalies found ; and, from the amount of aluminic sili- 
cate, it may be judged how perfectly the clay was de- 
composed by the previous treatment with sulphuric acid. 

h. According to A. Miiller, the relative j^roportion of 
silicates and quartz sand in a soil can be determined with 
accuracy by digestion with phosphoric acid at a certain 
temperature; all the silicates are decomposed by this 
treatment, and the silica is se2)arated in a gelatinous form 
while the quartz sand remains unchanged. 

For this purpose a syrupy acid is required containing 
40-45° I g of anhydrous acid; it may be obtained by con- 
centrating the commercial acid. 

The insoluble residue to be treated witli the acid must 
be very finely pulverized, but it need not be levigated ; 



§ 104. MISCELLANEOUS ESTIMATIONS. 183 

the amount of phosphoric acid required depends upon 
the amount of silicates present, and at least 15-20 grms. 
should be taken for 0.5-1.0 grm. of the substance. The 
mixture is heated in a platinum dish in an air-bath to 
190-200° C, and digested five or six hours at this temper- 
ature, while constantly stirred with a platinum sj^atula. 
The resulting mass is boiled several times with water 
containing V\ ^ of sodic hydrate, the clear liquid decanted 
off each time, and the sandy residue itself is finally 
brought on the filter and washed carefully with acid, alkali, 
acid again, and finally with w^ater, ignited and weighed. 

MISCELLANEOUS ESTLMATIOXS. 

101. a. Humus, — Weigh out 5-10 grms. of the air- 
dried soil, pour over it 200 c.c. of water in the flask of 
the apparatus for determining carbonic acid (§ GO, b), and 
30 c.c. of concentrated sulphuric acid; shake the mixture 
gently and let it stand some time until it has become 
quite cold, meanwhile changing the air in the flask sev- 
eral times by blow^ing into it, so as to remove all the car- 
bonic acid expelled from carbonates in the soil by the 
sti'onger acid. 

Now, put 7-8 grms. of coarsely pulverized potassic di- 
chromate in the flask (or, better still, 5 grms. of pure 
chromic acid), or such a quantity that there wall be 17 
parts of chromic acid for one of organic matter, as de- 
termined, approximately at least, in the beginning, by ig- 
nition (§ 98, a) / apply a gentle heat, and proceed to 
collect the carbonic acid evolved as in § 60, J, except that 
a U tube filled with iron wire should be interposed bc- 
tw^een the flask and the U tube ff\ to absorb chlorine, 
and except, also, that no nitric acid need be added to 
the substance. Towards the close of the operation, boil 
the contents of the flask five minutes, and finally draw 
air through in the usual manner. The carbonic acid is 



184 § 104. ANALYSIS OF SOILS AND ROCKS. 

set free by the oxidation of the humus by the chromic 
acid. 

Since humus contains on an average 58°| ^ of carbon, 
multiply the quantity of carbonic acid found by 0.4702, 
for the amount of humus. 

The difference between the sum of the humus and the 
nitrogen and the total loss suffered on ignition (§ 98) 
gives the amount of water, chemically combined or other- 
wise retained at 100° C. 

Some information in regard to the nature of the or- 
ganic matter, and the extent to which decay has pro- 
gressed, may be obtained by comparing the amount of 
humus, or of the carbon in it, with that of the nitrogen, 
by a microscopic examination of the various products 
of the silt analysis and by the loss suffered by these c:i 
ignition, and also by the following tests. 

1. The reaction of the soil or of the humus contained 
in it, which is tested by allowing moistened lumps of the 
soil to remain in contact with carefully prepared blue and 
red litmus-paper; a change from blue to red may be 
caused by carbonic acid, but, if the red color remains 
after the paper is thoroughly dry, the change was due to 
acids of the humus, unless the soil gives the same reaction 
after gentle ignition, in which case it may have been 
caused by acid sulphates. 

2. Mix 100 grms. of the soil with 200 c.c. of a stand- 
ard ammoniacal solution of calcic nitrate of such a 
strength that 200 c.c. contain 1 grm. of lime, and an 
amount of ammonia chemically equivalent to this amount 
of lime. After frequent shaking of the mixture in the 
course of 24 hours, filter, and determine lime in a measur- 
ed quantity of the filtrate ; the lime that is missing was, 
according to Knop, absorbed by the humus, and may be 
taken as an approximate measure of the amount of the 
same. 

3. To determine the amount of organic matter, mainly 



§ 104. MISCELLANEOUS ESTIMATIONS. 185 

in the form of humus, that is extracted from the soil by 
water or alkaline solutions, the following method is given 
by Schulze. Boil 10 grnis. of soil 15 minutes with 200 
c.c. of a solution containing 0.5° 1^, of potassa, bring the 
volume of the whole to 250 c.c, pour the liquid on a dry 
filter, or through dry, fine-grained sand with which the 
throat of the funnel is stopped ; put 4-G c.c. of the filtrate 
in a flask of about 200 c.c. capacity, dilute with about 100 
c.c. of water, and determine organic matter in 100 c.c. of 
this solution by means of standard solutions of potassic 
permanganate and oxalic acid (§ 91, e). 

h. Ammonia* — The amount of ammonia existing al- 
ready formed in soils is nearly always very small, since it 
is so readily converted into nitrates. 

To determine it by Schlossing's method (§ 47, ^), treat 
50 ffrms. of soil with 40 c.c. of a cold saturated solution 
of sodic hydrate. After 48 hours remove the acid from 
under the bell-jar, titrate it, stir the soil in the watch- 
glass, put another measured portion of acid in the proper 
vessel, and, after 48 hours, titrate this also with the 
standard sodic solution. If no more ammonia was set 
free during the second period, the first determination 
may be considered suflicient ; if more was set free, it 
should be added to the first quantity found, and a new 
2^ortion of acid should be put in, in the place of the last, 
and tested after 48 hours. 

It may also be desirable to estimate the ammonia that 
is set free on heating the soil with magnesia. Pour 500 
c.c. of water containing 5 grms. of freshly ignited mag- 
nesia over 100 grms. of soil, mix"the whole well together, 
and proceed to distil ofi" the ammonia (§ 47, c). 

Probably no great reliance can be placed on any method 
of determining ammonia in soils. 

c. Nitric acid. — The accurate determination of nitric 
acid is not difiicult, as the nitrates are so easily extracted 
from the soil by water. 



186 § 104. ANALYSIS OF SOILS AND HOCKS. 

To 1000 grms. of the soil add water enough to make 
2000 c.c. with that ah-eady in the soil, shake the mixture 
frequently in the course of 48 hours, decant and filter 
1000 c.c. through a dry filter, add some sodic carbonate 
to the filtrate, evaporate the solution to a small bulk on 
the water-bath, and divide the residue into two equal 
parts. Determine nitric acid in each portion, represent- 
ing 250 grms. of soil, in the usual manner (§ 62 ci). 

d. Cllloi'ine. — To determine this, add enough water to 
300 grms. of tlie air-dried soil to make 900 c.c. with what 
is already contained in it, shake the mixture frequently 
in the course of 48 hours, decant and filter 450 c.c. of the 
liquid, add a little sodic carbonate to the filtrate, evapo- 
rate to about 200 c.c, filter again, supersaturate the fil- 
trate, which represents 150 grms. of soil, with nitric acid, 
and precipitate the chlorine in the acid solution with 
argentic nitrate (§ 63). Treat the precipitate as one pro- 
duced in the presence of organic matter. 

e. Suipliur. — It often happens that a much larger 
amount of sulphuric acid is found in the soil after ignition 
than before, indicating that a notable quantity of sul- 
phur exists there as sulphuret, or in some organic combi- 
nation. To determine the total amount of sulj^hur in the 
soil, mix with 50 grms. of it, 1-2 grms. of pure saltpetre, 
moisten the mixture in a platinum dish with a solution of 
pure potassic or sodic hydrate, free particularly from sul- 
phates, dry, and heat gradually to a red heat ; when the 
mass is cool, boil it with^ dilute hydrochloric acid to 
which a little nitric has been added, evaporate to dryness, 
and eliminate silica in the usual way, but without weigh- 
ing it ; add water to the filtrate from the silica, and pre- 
cipitate sulphuric acid with baric chloride. 

/. Hydrated aliimiiilc and ferric oxides, — To deter- 
mine the quantity of these substances, that, according to 
Knop, play so important a part in the absorbent action 



§ 104. MISCELLANEOUS ESTIMATIONS. 187 

of the soil for valuable elements of plant-food, treat 100 
grms. of the soil with 200 c.c. of a hot solution contain- 
ing in one litre 100 grms. of tartaric acid, 10 grms. of 
oxalic acid, and ammonia in slight excess ; shake the mix- 
ture frequently for 15 minutes, filter, and determine 
alumiiiic and ferric oxide in a measured quantity of the 
filtrate (§ 52). The oxalic acid in the solvent serves to 
prevent lime from being taken up by the tartaric acid. 
In order to prevent alumina also from being dissolved, 
Miillcr recommends the use of Seignette salt instead of 
ammonic tartrate. 

g. FerrOElS ©xMe. — To determine this at least approx- 
imately, pour 60 c.c. of hot concentrated hydrochloric 
acid over 30 grms. of soil in a flask ; after having added 
a few crystals of sodic carbonate, if the soil contains but 
little carbonate, close the flask with a cork through which 
passes a short tube bent at a right angle, put the flask in 
an inclined position on the lamp-stand, and boil the mix- 
ture some time. Add a considerable quantity of ammonic 
chloride to the solution, whereby the tendency of the 
ferrous oxide to absorb oxygen is very much lessened, 
dikite with a large quantity of hot water, almost neutral- 
ize the acid with ammonia, and j^i'ccipitate the ferric 
oxide in the solution with as little sodic acetate as possi- 
ble (§ 93, ^, 1 ) ; filter the hot liquid rapidly through a 
large, coarse filter, and wash the contents of the filter 
several times with hot water; heat the filtrate and wash- 
ings to boiling, add some hydrochloric acid, oxidize the 
ferrous oxide by the addition of a few crystals of potassic 
chlorate, remove the lamp, and precipitate this solution 
with sodic acetate, filter, wash, and weigh. The ignited 
residue is ferric oxide, from which the corresponding 
amount of ferrous oxide can be calculated. 



188 g 105. ANALYSIS OF SOILS AXD BOCKS. 

ABSORPTIVE PROPERTIES OF THE SOIL. 

W5t To determine the coefficients of absorption of the 
soil for the more important elements of plant-food, treat 
125 grms. of the air-dried soil Adth 500 c.c. of a '1^^, 
atomic solution, that is, a solution containing in 1 litre ^1^^ 
of an equivalent expressed in grammes, of amnionic chlo- 
ride ; shake the mixture frequently during a cold digestion 
of 24 hours, decant and filter as large a portion of the 
liquid as possible, and determine the loss of the salt in a 
measured aliquot part of the filtrate. In some cases it is 
desirable also to make a complete analysis of this filtrate 
in order to learn what elements have taken the place of 
the ammonium in the solution. 

Make similar experiments with 2:>otassic chloride, mag- 
nesic chloride, calcic chloride, hydric disodic phosphate, 
sodic chloride, and sodic silicate. 

Or, according to Knop's method, dissolve together -po- 
tassic and calcic nitrate, common potassic phosphate, and 
magnesic sulphate, in a litre of water, in such a propor- 
tion that the solution shall contain 1.5 grms. of each com- 
pound, estimated as anhydrous salt. Treat 125 grms. of 
soil with 500 c.c. of this solution, shake the mixture fre- 
quently during 24 hours, filter off 300 or 400 c.c, and 
make a complete analysis of the solution, according to 
Scheme I., a and b, and determine chlorine in the usual 
manner in another portion of the same solution (§ 63). 

STATEMENT OF THE RESULTS OF THE ANALYSIS. 

106. The following Scheme is intended to assist the 
analyst in putting together the results of a soil analysis ; 
it is conformed mainly with the directions given by 
Wolff, and the percentages, though hypothetical, do not 
differ much from the average results of the later analyses 
of soils that have been made ; as the plan is given merely 



§ 106. STATEMENT OF EESULTS OF ANALYSIS. 189 

for the i^urpose of illustrating the manner of stating the 
results of the analysis, many of the determinations which 
are described in the foregoing pages are not noticed here. 
With this partial guide, no difficulty will be found in 
stating the whole result of the w^ork in an intelligible 
manner. 

MECHAXICAL ANALYSIS. 

100 x^arts of tlie air-dried soil yielded 

Water, expelled at 100°, 9.34: 

Residue ou 3 mm, sieve, 6.05, containing volatile matter 0.1 

'^ 1 '' " 7.69, '^ " " 0.86 

Silt in Fmmel No. 2, 34.9.5, " " " 8.73 

" " " " 3, 17.7, " " " 3.16 

" " " " 4, 5.65, " " " 0.82 

81.38 
Fiuccbyand finest sand, 18.62 " " *' 2.48 

100.00 Total loss on ignition of 

soil dried at 100' 10. 15 



190 



§ 106. A]S"ALYSIS OF SOILS AND EOCKS. 



CHEMICAL ANALYSIS. 



100 parts of the soil dried at 100° yielded 



l|l 

o -^ « 
Bo r 



Acids of humus ..3.25 

Humus coal 1.75 

Other organic matter. 1 . 25 

Ammonia 0.02 

Nitric acid 0.009 

Total nitrogen. 0T0288 

Water chemically combined or 

otherwise retained at 100° 1 .221 

7.500 



Soluble in water 2.10 

Soluble in alkali 1.25 

containing nitrogen 0.01 

0.0165 

0.0023 



Carbonic acid (det. in another portion). 0.14 

Lime 0. 17 

Magnesia 0.50 

Ferric oxide , 5.05 

Manganic oxide traces 

Alumina 4.20 

Potassa 0.06 



J Soda, 



0.02 

Phosphoric acid 0.15 

Sulphuric acid 0. 04 

Silica 0.35 

Chlorine (det. in aqueous solution) 0.073 

Deduct oxygen equivalent to the chlorine 



10.753 
. .003 

10.75 



'■--o.. 



Sow 



fLimo 0.31 

Magnesia 0.96 

And so on, as in the statement of the analysis of the 
solution in cold acid, with the exception of Chlorine, 
and Ihe addition of Silica, (dissolved out of the resi- 
due insoluble in hot acid, by boiling sodic carbon- 
ate) 



15.24 



r Volatile matter expelled on ignition 1 . 82 

Lime 0.21 

Magnesia 0.31 

Ferric oxide 1.03 

Alumina 1.76 

Potash 0.12 

^ Soda 0.20 

Phosphoric acid . 15 

Silica, in solution 0.14 

'• (dissolved out of the residue insoluble 

in H2SO4 by boiling NaoCOa . - . . . 4.56 
10.30 






CO d 



c.^ 



f Lime tr 



ace 



Magnesia " 

.0 .;§£.;-. I Ferric oxide 0.00 

"^O -S--^ Alumina 6.91 

arJj'p^>^^^ Potassa 3.20 

Soda 2.11 

Silica 44.00 






56.22 



§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 191 

100 parts of soil dried at 100° C. contain of day AI2O3 SSiOs, 

2HijO, estimated from tlie alumina and silica dissolved by acids 

(See Table III). 

a. In the hydrocliloric acid solutions 4.56 

h. " " sulphuric acid solution 4.41 

100 parts of soil dried at 100° contain of 
a. Potassa feldspar^ K20,3Si02, ALOs, 38102, estimated from the 

potassa in the solution by hydrofluoric acid. (See Table III.).18.94 
h. Soda feldqmr^ NaoOjSSiOo, AloOsjoSiOa, estimated from the 

soda in the solution by hydrofluoric acid 17.85 

c. Clay^ imdecomposed by the i^revious treatment with sulphuric 

acid, estimated from the alumina in the solution by hydro- 
fluoric acid in excess of what is required for the feldspars 0.30 

d. Pure quartz sand, estimated from the silica in excess over what 

is required for the feldspars and clay 19.11 

(Estimated also from the determination made with the aid of 
phosphoric acid). 
100 parts of soil dried at 100° C. yielded to water }{ saturated 
with carbonic acid 
Volatile matter, expelled on ignition of the residue left by evapo- 
ration of the extract 0.15 

Mineral matters 0.19 

0.34 
THE PHYSICAL QUALITIES OF THE SOIL. 

107. Experiments for testing the physical qualities of 
the soil, and for comparing different soils in respect to 
these qualities, should be made with soils of the same de- 
gree of dryness and mechanical division, and with tolera- 
bly large quantities, and the observations should be made 
under circumstances resembling those as closely as possi- 
ble, by which the soil is affected in the field. The fol- 
lowing methods have been carefully tested by Wolff 
himself, and he vouches for their reliability. 

The soil must be completely air-dried, pulverized in a 
porcelain mortar with a wooden pestle, or rubbed betAveen 
the hands to break up the lumps that were formed in 
drying, and passed through a sieve witli meshes 3 mm. 
wide. 



192 § 107. ANALYSIS OF SOILS AXD EOCKS. 

a. Relation of the Soil to Vapor of Water. — 1, 
Power of retaining hydroscopic water m its pores. — This 
is measured to some extent by the determination of hy- 
groscopic moisture (§ 98). The proportion of humus 
remaining about the same, the power of the soil to retain 
moisture is very closely related to the amount of clay it 
contains, while this power is greatly increased by an 
increased proportion of humus. 

2. It may be interesting to observe the relation of this 
property of the air-dried soil to the temperature,— 
For this purpose, spread a layer of soil, accurately weigh- 
ed, about 3 mm. thick over the bottom of a shallow zinc 
tray, and note the changes in weight from day to day, 
wdien it is exposed to direct sunlight while protected 
from currents of air, or when exposed to a temperature 
of 20°, 30°, and 40° C. 

Also, expose the goU to an atmosphere that is saturated 
with moisture^ by putting it in the same shallow tray to- 
gether with a shallow vessel of water, under a bell-jar, 
and weighing it three or four times every 24 hours. An 
empty tray of the same size should be put under the same 
bell-jar, and any changes in the weight of this deducted 
from the differences in the weight of the other. 

Sandy soils and loams usually become nearly saturated 
in an experiment like this, in the first 24 hours, and 
change but little in weight thereafter. 

The quantity of water absorbed varies of course with 
the temperature, and with the kind of soil ; but these 
variations are confined within narrower limits than when 
the soils are exposed to the air under ordinary circum- 
stances. The amount of water absorbed from this satu- 
rated atmosphere ranges between 0.2 and 2.5° |g of the 
w^eight of the completely dry soil. 

The same soil, in its tray, may he exposed to the night 
air^ to determine the amount of w^ater that it will con- 
dense from the atmosphere under these circumstances ; 



§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 193 

careful observations should be made, at the same time, of 
the temperature, the clearness of the sky, and the 
amount of the dew-fall, and the experiment should be 
performed over a grass plot as well as over a freshly 
stirred soil. 

With an average dew-fall, the amount of water taken 
up by a soil above what it contains in the air-dried state 
varies, with diiferent kinds of soil, between 0.4 and 1.8° 1^ 
of the weight of the completely dried soil. 

Finally, to^est the effect of the depth of the soil on 
its power of absorbing moisture under these different cir- 
cumstances, several trays or boxes, of say '!„, I'l^? ^5 ^^^ 
6 cm. deep, and 5 cm. square, may be filled with air-dried 
soil, in all cases equally dry and finely pulverized, and 
the whole exposed to the ordinary atmospheric influ- 
ences, or to a saturated atmosphere, or to the night air, 
in the manner directed above. 

By such experiments we may determine how much 
moisture is absorbed by layers of soil of different thick- 
nesses within a certain length of time, how far the moist- 
lu-e penetrates into different soils in equal times, and how 
long a time is required to saturate layers of different" 
thicknesses in a saturated atmosphere. 

b. The Relation of the Soil to Liquid Wateii ix its 
Pokes.— 1. To dctermme the power of the soil to retain 
liquid water m its pores, construct a zinc box, 17 cm. deep, 
and 3 cm. square, and pierce its bottom with numerous 
small holes ; lay over this bottom a piece of moistened 
fine linen, and weigh the box ; then put in a small quan- 
tity of the properly dried and pulverized soil, tap the 
box gently on the table a few times, and proceed in the 
same manner until the box is full, and weigh again. 
Then immerse the bottom of the box in water to the 
depth of 3-4 mm. ; the water appears at the surface of 
the soil sooner or later, according to the nature of the 
latter ; let the apparatus remain in the water until it suf- 
9 



194 § 107. ANALYSIS OF SOILS AND EOCKS. 

fers no further change m weight, and then calculate the 
amount taken up by 100 parts of the air-dried soil. 

As this box, with its wet soil, is used subsequently for 
experiments in the course of which the soil is dried 
again, this trial may then be repeated ; some soils shrink, 
while drying, to a greater extent than others, and it will 
be found that, in this second trial, the power of holding 
water will not be the same as at first. The difference, 
how^ever, is but slight. 

The power of a soil to hold liquid water increases with 
the proportion of humus, but diminishes as the quantity 
of clay increases. A strong clay soil may retain 27.3" 1^, 
a moderately heavy soil 30-31° j^, a sandy loam 33-36° 1^, 
a black loam, rich in humus, 41° 1^. When some soils, 
that had been tested as above, were tested also in their 
natural position in the field, after a rain of 14 days, when 
they might be supposed to be saturated, they w^ere found 
to contain 10° 1^ less than w^as indicated by the results of 
experiments in the laboratory ; hence, the determinations 
made with small quantities in zinc boxes, appear to have 
value only in so far as they enable us to compare the 
water-holding powers of different soils. 

2. To detcrmme the readiness with which water evap- 
orates from the soil, the wet or damp soil may be ex- 
posed, in a shallov^ tray, to the air, at the common sum- 
mer temperature, or at that of the laboratory ; but so 
long as a considerable proportion of water is present, the 
rate of evaporation remains about the same for all soils, 
provided only that the same amount of surface is exj)osed; 
it is also very slow, months being required to bring 100- 
150 grms. of soil, in a layer no more than 4-6 cm. thick, 
to the condition of air-dried soil. 

When, however, natural circumstances are more closely 
imitated, and a sufiiciently thick layer of soil is experi- 
mented v/ith and exposed to the usual alternation of direct 
sunlight and shade, the characteristic differences of soils 



§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 195 

aj^pear. For a standard of comparison it would be well 
to carry on, simultaneously, one or two similar trials with 
soils of a marked character, such as a very strong clay 
soil and a very sandy one, that have been tested before 
in this respect. 

To make the determination, use the zinc box filled with 
wet soil, that was obtained in testing the water-holding 
power ; put each box with its contents in a second box 
of thick j^asteboard, into which it just fits, and then put 
all these pasteboard boxes close together in a third 
wooden box, just as deep as the zinc boxes ; provide the 
wooden box with a cover, in which holes are so cut that, 
when the cover is on the box, only the surface of earth in 
each zinc box is exposed. 

Put the whole where the sun's rays can fall on the soil, 
and weigh each zinc box with its contents every two or 
three days, and during a length of time varying from tAvo 
to four weeks, according to the weather ; frequent ob- 
servations of the temperature and the state of the sky 
should be made, while the evaporation is going on. 

It will be observed that, in the beginning, the rate of 
evaporation is about the same for all the varieties of soil 
under examination, even when exposed to the rays of a 
hot sun ; after a time the sandy soils begin to lose weight 
more rapidly than those in which clay or humus pre- 
dominates ; the difierence increases up to a certain point, 
and then begins to diminish, until, after a time, the rate 
of evaporation is nearly the same again for all ; this con- 
tinues for a time, and then the clay and humus soils begin 
to lose water more rapidly than the light loam, because 
the latter is, by this time, nearly air-dry. 

It is of course more important to watch carefully the 
rate of evaporation, from the time when it begins to differ 
in the different soils, to the time when it again becomes 
about the same for all. 



196 § 107. AXALYSIS OF SOILS Al^D KOCKS. 

8. To determine the ease with which water perco- 
lates through the soil, construct a zinc box about 25 cm. 
high and 3 cm. square, with a funnel-like bottom ; put 
some cotton in the bottom, so as to close up the throat 
of the funnel, and fill the narrow tube, and extend out a 
little at the mouth of the latter. Fill the funnel above 
the cotton with coarse quartz sand, moisten the cotton 
and gand with water, and weigh the apparatus ; then 
carefully fill the box with the properly prepared earth, 
putting in small quantities at a time, and tapping the box 
on the table after each portion is added ; when the box is 
filled to within 9 cm. of the top, weigh the whole again ; 
then, just saturate the soil by carefully pouring on water 
in small quantities at a time, until it appears at the 
bottom ; when it has ceased to drop through, weigh the 
box and its contents again, and the result may be used 
to confirm that obtained before for the water-holding 
power of the soil. 

Now carefully fill the box with water to within 1 cm. 
of the top without disturbing the surface of the soil, 
cover with a glass plate, and observe how long a time is 
required for 50 c.c. of water to pass tli rough. If the 
operation is repeated, by filling the box with water again, 
after the first quantity has passed through, it will be 
found that a somewhat longer time is i-equired ; three 
such tests may be made, and the mean of the three re- 
sults taken. 

4, To determine the rapidity with which water will 
move upwards in the soil, fill a glass tube about 80 cm. 
high and 1.5-2 cm. in diameter, graduated in cubic cen- 
timetres, and closed at its lower end with a piece of fine 
linen that is tied over the end, with the air-dried soil, tap- 
ping the tube gently on the table while filling it ; then 
immerse the lower end of the tube in water 3-4 mm. 
deep, and observe how long a time is required for the 
water to rise to a height of 70 or 80 cm., or how high 



§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 197 

the water will rise in 24 or 4S hours ; it will be found 
to rise more slowly in humus and clay soils than in light, 
sandy ones. 

5. The rapMity witli whicii water will make its way 
downwards in the soil may be determined in the same 
tube, partly filled with a fresh quantity of earth ; fill the 
tube above the soil with water to the depth of 4-8 cm., 
and note the time required until it has reached a given 
depth, or how soon the water disappears from the surfiice 
of the soil, rmd also how far a given quantity, that is in- 
sufiicient to make its way through and moisten the soil 
quite to the lower end, will penetrate downwards. 

It will be found that the same quantity of water will 
go furthest in a fine loam or a sandy soil. 

c. The Relation of the Soil to Heat. — 1, To 
determine the power of the soil to absorb heat, fill a 
cubical zinc box, about 6 cm. square, with soil, expose it 
several hours to the direct rays of the sun on a hot day, 
carefully observe the temperature in the sun during the 
experiment, and the elevation of temperature in the up- 
permost centimetre of the soil. The zinc box should be 
inclosed in a box of thick pasteboard, and tliis in a wooden 
box, to prevent access of heat at the sides. 

It may also be interesting to observe the heating power 
of the sun's rays on the soil, while it is in a more or less 
moist condition, say with 5, 10, or 20° 1^ of Avater, more 
than that naturally present in the soil. Such determina- 
tions may be made by exposing about 50 grms. of the 
moistened soil for several hours in a glass flask to the 
direct rays of the sun, and noting the changes of tem- 
perature. 

2. The power of the soil to conduct heat may be de- 
termined by putting the same box, as used in the previ- 
ous experiment, into hot water, and observing how long 
a time elapses before the temperature of the earth in the 



198 § 107. AXALYSIS OF SOILS AND ROCKS. 

centre of the box has reached a given yjoint, say 70° or 
80° C. 

3, The power of the soil to retain heat may be de- 
termined by exposing the box of lieated soil, obtained in 
either of the preceding experiments, to the common tem- 
perature of the air in the shade, and observing how long 
a time is required for the soil in the middle of the box to 
cool to the temjDcrature of the air, or to a given point, as 
20° or 25° C. 

The behavior of the soil with respect to the heat of the 
sun and of the atmosphere is of great agricultural im- 
portance, and should be more carefully examined than 
has hitherto been the case, by the careful performance of 
experiments like those described above, and by series of 
observations on tlie temperature of the soil in the field at 
various depths, ranging from 3 cm. down to one metre or 
more. 

d. The Specific Gravity of the Soil. — 1, This may 
be determined in the usual manner for a powder (§ 35, V). 

A soil rich in humus is specifically the lightest, and 
coarse sandy soils are the heaviest. 

2. The absolute weight of the soil is determined by 
filling a glass vessel, or a cubical zinc box, Avhose weight 
and capacity are known, with it, tapping the vessel occa- 
sionally on the table while filling it, and weighing it. The 
weight of a cubic metre or a cubic foot can then be cal- 
culated from the result ; the apparent specific gravity 
can be estimated by the ratio between the weight of this 
volume of soil and that of an equal volume of water. 

3. The apparent speciSc gravity of the soil dried at 

100° C. may be estimated by subtracting the A^olume of 
the water contained in the quantity of air-dried soil that 
was weighed in this experiment from the volume of the 
soil, and then a volume of water equal to tlie remainder is 
taken for the divisor, and the weight of the soil dried at 
100° for the dividend. 



§ 107. THE PHYSICAL QUALITIES OF THE SOIL. 199 

4. The porosity of the soil, or the ratio between the 
volume of the solid particles and that of the spaces in it 
filled with air or moisture, is estimated by dividing the 
apparent specific^gravity of the soil, dried at 100°, by the 
real specific gravity. Or if, for example, 2.5445 = the 
real specific gravity of a certain soil, and 1.099 its ap- 
parent specific gravity, then from the proportion, 

2.5445 : 1.099 = 100 : 43.2, 
we get the volume of the solid particles in 100 parts of 
the soil, and 100-43.2 = 56.8 = the volume of the pores. 

The porosity of the soil, just as it lies in the field, may 
be estimated in a similar manner, by taking as the volume 
of the soil the space that was occupied by the quantity 
taken out to be weighed. 

To determine the volume occupied by the soil wheo 
completely saturated with water, determine the volume 
of 40-50 grms. of the air-dried, pulverized soil in a 
graduated tube, that was filled with the earth in small 
portions at a time, with occasional tapping on the table, 
shake the soil up well with water containing 0.5° 1^ of am- 
nionic chloride ; then let the whole stand quietly, while 
the solid particles collect together in the lower part of 
the tube, and observe the volume occupied by this wet 
soil. By dividing the second volume by the first, the re- 
sult is put in a convenient form for comparison. 

e. CoNSisTEXCY, Tenacity, axd Adhesive Power op 
THE Soil. — The consistency of the soil when dry, its 
tenacity, and the force with which it adheres to wood and 
iron, are very important qualities ; but it is hardly pos- 
sible, by any of the methods in use for estimating them, 
to get even approximately accurate results with small 
quantities of soil. The following methods were devised 
and used by Schiibler thirty years ago. 

1, To determine the consistency of the soil, or the 
force with which its particles cohere together when dry, 



200 § 108. ANALYSIS OF SOILS AND EOCKS. 

knead a small portion of it into a thick dough with water, 
and, with a spatula, make several prisms 5 cm. long, and 
1 cm. square on the end ; let them dry in the air, and 
then observe w^hat weight must be laid on the back of a 
knife in order to force it through each one. The same 
prisms may be used to determine how much the soil 
shrinks on drying, by noting the difference between their 
lengths when wet as at first, and after they are dry. 

2. To (Ictermmc the force with which the soil adheres 
to wood or iron, fill a cubical zinc box about 6 cm. square 
and deep, whose bottom is pierced with small holes, and 
covered with a piece of linen, with the soil, shaking it 
down frequently wdiile filling ; then immerse the bottom 
of the box in water, and, when no further increase of 
Av eight is observed, lay a smooth piece of beech W'Oocl, 3 
cm. square, on the wet surface of the soil, press it dowm 
for the space of ten minutes, by a weight of 100 grms., 
attach the disk to one arm of a balance, and observe what 
weight must be put in the pan connected with the other 
arm, in order to detach the disk from the soil. Try a 
similar experiment with a disk of iron. 

EXPERIMENTS WITH PLANTS IN CONNECTION WITH ANALY- 
SIS OF SOILS. 

108. The further development of soil analysis on one 
hand, and its simplification on the other by eliminating 
useless or unnecessary determinations, can be accom- 
plished only by combining suitable experiments w4th 
modes of culture and manuring, and growing plants, with 
accurate analyses of the soils used. 

In the field but little can be done in this way, since so 
much care and labor are required, in order to obtain a 
tolerably fair representative sample of the soil, even of a 
small plot. 

iSTot seldom, however, a more luxuriant vegetation is 



§ 108. EXPEEIMENTS AVITII PLANTS AND SOILS, 201 

observed in one part of a field than in another, although 
the nature of the soil and the mode of treatment are ap- 
parently the same throughout ; in such a case, much may 
possibly be learned, by a careful comparison of the amounts 
of the crops taken from the two parts of the field, and a 
search for the cause of the difference by a careful exami- 
nation of the soil. Of course the nature of the subsoil 
should be ascertained, down to the depth of a metre or 
so, in order to be sure that the cause of the phenomenon 
does not lie there, perhaps in some accumulation of water, 
or a great difference in the mechanical or physical charac- 
ters of this subsoil. 

Actual experiments with manures and growing plants, 
to be combined with soil analysis, are best made in boxes 
of soil that has been carefully sifted and mixed ; a perfect 
sample of such a soil can be obtained without difiiculty. 

The wooden boxes to contain the soil for these ex23eri- 
ments may be made about one metre deep, and half a 
metre square, and with several holes through the bottom. 
They should be set in the ground in a grass plot, so that 
they will project but 3-5 cm. above the surface. The 
soil with which they are to be filled should be pulverized 
when in a very moderately moist condition, by rubbing 
it between the hands, or with a wooden pestle in a porce- 
lain mortar, and passed through a sieve with meshes G-8 
mm. wide ; an ample quantity of it should be provided, 
so that there may be enough for the analysis and for all 
possible contingencies, besides wdiat is required to fill up 
the box. 

To fill the box, put a layer of gravel 5-8 cm. thick 
over the bottom, and then add the soil, pressing it down 
gently, as it is put in in small portions at a time ; then 
pour a quantity of rain-water over the soil, equal to 
about half that which it can retain in its pores ; stir up 
the surface and fill with more soil, up to the edge of the 
box, and, if possible, before sowing the seed, or putting 



202 § 108. ANALYSIS OF SOILS AIS^D ROCKS. 

in plants, let the whole stand several weeks, so that it 
may settle together and assume a j^erfectly natural con- 
dition. 

If the boxes, when put in place, are not surrounded by 
grassy turf, the same plants as those cultivated in them 
should be grown around them, so that there can be no 
disturbing influences from fresh soil. 

When the seed is to be sown, put in more fresh soil if 
it is necessary, in order to bring tlie surface up even with 
the edge of the box. In sowing the seed, and in the sub- 
sequent cultivation of the plant, the usual rules of good 
culture should be observed as fir as possible, as respects 
depth of sowing, distance apart of the plants, and other 
matters. For experiments with the cereals, Avhich are of 
the greatest importance, oats and rye are best, since these 
plants arc less liable to disease, or to be destroyed by 
birds. 

The following are a few of the great number of inter- 
esting experiments that can be performed in these boxes 
of prepared soil. 

Three or four soils may be prepared, differing great- 
ly in the amount of sand and clay they contain, but 
closely resembling each other as regards the lime and hu- 
mus. Not only the quantity of the crop should be ob- 
served, but also its quality^ such as, in the cereals, for 
example, the proportion of grain, straw, and chaff, of 
light and heavy grains, the specific gravity of the grain, 
the number of the stalks and the degree of maturity at- 
tained by them, the weight of the stubble and main roots, 
and the proximate chemical comjoosition of the different 
parts of the plant. 

With such observations as these, combined with an ac- 
curate knowledge of the composition of the soil, we 
should soon learn whether any direct relation exists be- 
tween the proportion of plant-food in the soil, that is 
soluble in water or cold or hot hydrochloric acid, and 



§ 108. EXPERIMENTS WITH PLANTS AND SOILS. 203 

the quantity or quality of the crop, or whether, as is 
probably the case, the proportion between the clay and 
these soluble substances, or, in other words, the physical 
character of the soil, exerts a controlling influence on its 
fertility. 

It w^ould be well to perform three experiments of the 
same character with each kind of soil, partly for the pur- 
pose of securing greater certainty in the results, and 
partly that the same soil may be used afterwards for other 
experiments. 

To test the question whether the substances in tlie soil 
til at are soluble in ])iiTe or carbonated water exert any 
essential influence ou its immediate productiveness, a trial 
may be made with a soil in its natural condition, and with 
the same or a similar soil, after it has been exhausted with 
w^ater in the manner described for the preparation of an 
aqueous solution for chemical analysis (§ 100). As, how- 
ever, it would be very inconvenient to exhaust such a 
quantity of soil in this way, as would be required to fill 
one of the boxes, this experiment may be performed with 
but 7-10 kilos, of soil, in smaller boxes, or in glass 
vessels. The plants should be watered ^yiih distilled 
water during the progress of the experiment. 

Valuable results may be obtained from experiments in 
which equal quantities of assimilable plant-food are added 
to difierent varieties of soil. 

The action of a full and complete provision of the ele- 
ments of plant-food on one kind of plant grown in the 
diflerent soils, sliould first be examined. For such a 
complete manuring, w^e need only to mix together acid 
potassic phosphate, calcic nitrate, potassic nitrate, and 
magnesic sulphate, so that the relative proportions of 
the bases in the mixture will be the same as in the ash 
of the plant to be cultivated. 

For this purpose, the boxes and soils employed in pre- 
vious years for trials with soils containing difi'erent 



204 § 108. ANALYSIS OF SOILS AND ROCKS. 

amounts of sand and clay may be used ; one box of each 
kind of soil should have nothing added to it, so as to have 
a standard with which to compare the effect of the ma- 
nuring in other soils of the same nature. From the aver- 
age crops of the 2:)receding year in all the boxes, an esti- 
mate may be made of the quantity of plant-food to be 
added. 

The soil to be manured is taken out of the box to the 
depth of 30 cm. ; ^ |^ of this is intimately mixed with the 
aqueous solution of the salts to be added, and this in its 
turn is intimately mixed with the remaining ^1^ of the 
soil, by rubbing the two together carefully between the 
hands ; the whole is then put back into the box. 

Instead of the solution of the above salts, the actual 
practice with manures may be more closely imitated by 
making an aqueous extract of a suj^erphosphate, deter- 
mining the amount of phosphoric acid in the solution, and 
dissolving therein the proper amounts of crude potassic 
chloride, sodic nitrate, and magnesic sulphate. 

In a similar manner, the effect of an increased propor- 
tion of humus in the soil may be studied, by letting some 
sawdust of a soft wood, free from resin, partly decay, 
making an aqueous extract of this, or of some other suit- 
able substance rich in humus, and mixing this solution 
with the soil in the way already described. 

Other matters that might be profitably studied in this 
connection are, the effect of lime, of the concentrated 
commercial manures, and the relation between the co- 
efficients of absorption of the soil for the various ele- 
ments of plant-food, and its fertility. 



§ 109. MARL. 205 

II. 

ROCKS AND THE PRODUCTS OF THEIR WEATHERING. 

109. The object of analyzing a rock, for agricultural 
purposes, may be to estimate the total amount of its con- 
stituents, or to determine its solubility and the readiness 
with which it would be disintegrated and converted into 
soil on exposure to the air. The method of the analysis 
AYOuld be much the same as that already described for the 
analysis of soils. A qualitative examination should pre- 
cede the quantitative one, in order to learn the best way 
of bringing' the mineral into solution, as well as what 
substances are to be separated and determined. 

The examination of the products of the weathering of 
a rock should be conducted in the same manner as a regu- 
lar soil analysis, by treating it with the same solvents in 
the same succession. 

The three more important substances that come under 
this head are marl, limestone, and clay, and some special 
directions for the analysis of each may be useful. 

MARL. 

As this substance is used by the former in its natural 
condition, it should be taken in a similar condition, for 
analysis, viz., air-dried and unignited. If taken fresh 
from the pit, it should be allowed to lie for a long time 
exposed to the air on filter-paper, until thoroughly dry. 

The most useful of the determinations mentioned belov/ 
are those of phosphoric acid and the alkalies, and the me- 
chanical analysis. 

The mechanical analysis. For this, which is of much 
importance, since the value of a marl usually depends 
largely on the fineness of the division of its particles, 
treat 30-50 grms., according to the amount of calcic car- 



206 § 109. ANALYSIS OF SOILS AND ROCKS. 

bonate contained in it, with dilute hydrocliloric acid in a 
flask, as long as there is any effervescence, wash the resi- 
due, boil it half an hour with water, and then subject it 
to the silt analysis (§ 97). 

Or, if it is desired to determine the fineness of division 
of the calcic carbonate in the marl, the whole may be 
subjected to the silt analysis without previous treatment 
with acid, and tlien the carbonate can be determined in 
the contents of each funnel. 

If the marl does not fall to a fine powder in water, it 
must first be sifted, as directed for the preparation of the 
soil for the silt analysis. 

For practical purposes, the following rough method of 
estimating the fineness of the marl will often answer. 

After treating 10 grms. of the marl with hydrochloric 
acid as long as there is any effervescence, pour a consid- 
erable quantity of water over the residue, with constant 
stirring, let the sand and heavier particles settle, and de- 
cant the turbid liquid holding clay in suspension ; repeat 
the same operation with the residue several times, until 
'the water is clear after the sand settles to tlie bottom, 
collect the latter on the filter, ignite, and weigh as coarse 
sand. 

The cheinlcal analysis. 

a. Water. — Dry about 10 grms. of the substance at 
100° C, and determine the loss of weight. 

h. Carbonic acid. — Determine this in 2-4 grms., as di- 
rected in § 60. 

For practical j^urposes, the following method will usu- 
ally yield sufiiciently accurate results. 

Weigh out 2-3 grms. of the marl in a flask of about 
100 c.c. capacity, moisten it with a little water, carefully 
lower into the flask a small test-tube, ^|^ filled with hydro- 
chloric acid, in such a way that no acid can escape into 
the flask, and weigh the whole ; then cause the acid to 
flow out of the test-tube into the flask by inclining the 



§ 109. MARL. 207 

lattej", and, wiiile the effervescence continues, let the flask 
lie in an inclined position, with the end of the test-tube 
partly stopping up its mouth. When the effervescence 
has ceased, blovv^ air into the flask to remove the carbonic 
acid gas, weigli the whole again, and count the loss as car- 
bonic acid ; the results will be within 0.25" 1^ of the truth. 

c. Lime and Ula^nesia. — Digest 2-3 grms. of the well- 
pulverized marl with dilute hydrochloric acid, and exam- 
ine the solution more particularly for lime and magnesia, 
as under b, Scheme lY., § 94. 

d. Phosphoric acid and the alkalies. — Allow 300 c.c. 
of concentrated hydrochloric acid (Sp. Gr. = 1.15) to act 
on 100 grms. of the well-pulverized marl in a large flask, 
for 48 hours at common temperatures, with frequent agi- 
tation ; (or, take 120 grms. of soil and 360 c.c. of acid, if 
ferric oxide and alumina are to be determined, and esti- 
mate them in ^ |g of the solution obtained ; this determina- 
tion, however, will not generally be important). 

Decant the solution from the insoluble residue, dilute 
with some water, filter, put the insoluble residue on the 
filter, and wash it first with cold and afterwards with hot 
water. Evaporate the filtrate to drynes's, and remove 
silicic acid. 

Examine the filtrate from the silica as under b, in 
Scheme I, § 94. 

If the marl contains a large proportion of clay, some 
of the phosphoric acid may remain undissolved by the 
cold concentrated acid. In this case, boil about 50 grms. 
of the marl one hour with 150 c.c. of concentrated acid, 
filter, eliminate silica, and proceed to determine phosphoric 
acid, as above. 

The insoluble residue, left after treatment of the marl 
Avith cold acid, and composed of clay and sand, is dried 
in the air-bath, left for a considerable time exposed to the 
air, and weighed. If from this we subtract the weight 
of coarse sand, obtained by the rough method in the 



208 § 109. ANALYSIS OF SOILS AXD EOCKS. 

mechanical analysis, we h.ave left the amount of fine sand 
arid cla}^ 

Treat this residue in the same manner as directed in 
§ § 102 and 103 for the treatment of the corresponding 
part of the soil. 

e. A determination of humus is generally unnecessary, 
but if desired, can be conducted as directed in § 104. 

f. A determination of nitrogen will rarely be needed, 
but may be made in the usual manner, with 5-10 grms. 
of the marl. 

g. Some marls, particularly such as are rich in clay, and 
contain but little sand, are much more effective after hav- 
ing been gently ignited. To test the marl in this respect, 
heat it to a low red heat in a muffle, with free access of 
air, and then make an aqueous extract of the ignited mass 
by treating 500 grms. ot it with 2000 c.c. of distilled 
water, with frequent agitation during a cold digestion of 
48 hours. Then filter off " \^ of the solution, or 1600 c.c, 
for the determination of the alkalies ; evaporate this solu- 
tion to dryness, eliminate silica in the usual manner, and 
estimate the alkalies in the filtrate from the silica 
(§ 93, G.). 

Another portion of 100 grms. of the ignited marl may 
be treated with 300 c.c. of concentrated hydrochloric acid 
in the cold, in the manner already directed, to estimate 
phosphoric acid, and, if desired, the alkahes again. 

A. Analyses of the green sand marl of New Jersey. 
(Cook.) 

Carbonic acid 2 

Lime 2.4 1.0 

Magnesia 0.4 2.0 

Ferric oxide 8.3 21.3 

Alumina 6.1 8.0 

Potasli 2.5 7.1 

Sulphuric acid 0.9 0.4 

Pliospliorlc acid 1.4 1.3 

Silica [soluble] 20.2 45.9 

Silica [insoluble sand] 49 9 4.0 

Water 7.1 8.1 

99.4 99.1 



§ 110. LIMESTONE AND LIME. 209 

LIMESTONE AND LLME. 

110. ((. If it is desired to examine the changes that a 
limestone has undergone in weathering, or to ascertain 
vv^hat it contains that may contribute to the fertility of 
the soil, it should, of course, be taken in its natural, air- 
dry, unignited condition. 

Pulverize it, and treat from 150 to 300 grms., according 
to the proportion of clay or other silicates present, Avith 
cold and hot concentrated hydrochloiic acid, with sul- 
phuric acid, and so on, in the manner directed for the 
analysis of soils. The cold hydrochloric acid dissolves 
all the carbonates, commonly all the j^hosphoric acid, but 
only a small portion of the alkalies, even if a considerable 
amount of these is present. But this small quantity that 
is taken into solution should be determined, and the esti- 
mation can be effected, after removal of the silica, in the 
usual manner (Scheme I., a or b, § 94). 

The residue, insoluble in cold hydrochloric acid, is of 
great importance, agriculturally considered, for it is not 
seldom rich in potassa, and it should be examined with 
the aid of the silt analysis, as well as of hot hydrochloric 
acid, sulphuric acid, and hydrofluoric acid (§ § 101, 102, 
103). In one case, over 50°|gOf potassic feldspar was 
found in the sandy insoluble residue of a dolomitic lime- 
stone ; in another case little but pure quartz. 

h. By " burning " the limestone, it is essentially changed 
with respect to the solubility of its constituents, and j^ar- 
ticularly the alkalies, which become soluble in larger 
measure. Therefore, when a limestone is to be applied to 
the soil after being burned, it should be burned before 
being analyzed ; this may be accomplished by igniting it 
in a Hessian crucible through the bottom of which a hole 
has been broken, until, after cooling, a piece of it foils 
completely to a fine powder when moistened with about 
a third of its weisfht of water. 



210 § 110. a:n'alysis of soils and eocks. 

1. Ill this burned limestone, determine the alkalies 
soluble in water by treating 150 grms. with 1500 c.c. of 
distilled water, with frequent agitation during a digestion 
of 24 hours. Then pour off 1000 c.c. of the supernatant 
liquid, as clear as possible, filter, if the liquid is not per- 
fectly clear, remove silica as usual (§ 58, a), by evapora- 
tion to dryness and treatment with hydrochloric acid, 
and eliminate the alkalies as chlorides (§ 93, G). 

2. Digest another portion of 100 to 150 grms. of the 
burnt lime, according to its richness in silicates, 48 hours 
in the cold, with three times its weight of concentrated 
hydrocldoric acid, filter the mixture, and wash the resi- 
due, first with cold, and then with hot water. Determine 
phosphoric acid and the alkalies in this solution (Scheme 
I., § 94) ; no ferric chloride need be added. 

It sometimes happens that a considerable separation of 
gelatinous silica renders the filtration of the hydrochloric 
acid solution very difficult. In this case, evaporate the 
whole mixture to complete dryness, moisten the residue 
with concentrated acid, let it stand awhile, boil with di- 
lute acid, filter, and examine this filtrate for phosphoric 
acid and alkalies, as above. The solution Mill contain all 
that would ordinarily be dissolved by both cold and hot 
hydrochloric acid. 

Treat the residue, insoluble in cold hydrochloric acid, 
with hot acid, if not already so treated, and then with 
sulphuric and hydrofluoric acids (§ § 101, 102, and 103). 

c. To determine whether a limestone will yield good 
mortar lime, digest 4-5 grms. with dilute hydrochloric 
acid, evaporate the whole to dryness, after adding a few 
drops of nitric acid, boil the residue with acidified water, 
filter, wash, ignite, and Aveigh. A good limestone, for 
this purpose, should not leave more than 5 to 10° |„ of in- 
soluble matter. 

The solution may be examined for alumina, ferric oxide, 



§ 110. LIMESTOXE AND LIME, 211 

lime, and magnesia, according to Scheme I., § 9-4 ; man- 
ganese need not be noticed unless a qualitative analysis 
reveals its presence in considerable quantity. 

A determination of carbonic acid may be made to con- 
trol the results of the other part of the analysis. 

All the bases found should be calculated as carbonates 
in making up the final statement. 

d. To determine whether a limestone will make a good 
hydraulic cement, the course described in the preceding 
paragraph should be followed ; but the alkalies should be 
determined also, and the residue, insoluble in hydrochloric 
acid, should be examined with the aid of sulphuric and 
hydrofluoric acids {§ § 102 and 103). 50-60 grms. of the 
stone should bo taken for treatment witli hydrochloric 
acid. And, as the chemical analysis alone w^ill not furnish 
perfectly safe information in regard to the fitness of the 
stone for the purpose in question, portions of it should be 
ignited at various temperatures, and the resulting lime in 
each case pulverized and made into little balls with water, 
either alone or >vith sand, and tested under water, to see 
whether it hardens properly. 

e. If the cement already prepared is given for exami- 
nation, it will be important to determine the amount of 
gelatinous silica set free by the hydrochloric acid, as well 
as the lime, alumina, and alknlies. 20-25 grms. of sub- 
stance will usually answer for the analysis, since the stone 
is rendered more soluble by the ignition that is required 
to convert it into cement. 

Boil the residue, that is insoluble in hydrochloric acid, 
with sodic carbonate (§ 58, a^ 2), pulverize what is in- 
soluble in this agent very finely, and treat it with hydro- 
fluoric acid. 



212 § 111. ANALYSIS OF SOILS AND KOCKS. 

CLAY. 

llli This should be taken for analysis in its natural, 
air-dried condition, and examined by the same processes 
as have been given for the mechanical analysis of soils, 
and their treatment with acids. Different clays are very 
differently affected by these agents. 

Conclusions in regard to their agricultural value must 
be based upon their relative solubility in the acids used, 
and the composition of the part that is soluble in hydro- 
chloric acid, and of that which is made soluble by treat- 
ment with sulphuric acid. 

For technical purposes it will usually answer to treat 
10-15 grins, of the clay with 6-8 times its weight of con- 
centrated sulphuric acid, evaporate the mixture to com- 
plete dryness, exhaust the residue vv^ith dilute hydrochloric 
acid, eliminate sihcic acid from this solution, and estimate 
alumina, ferric oxide, manganese, lime, magnesia, and the 
alkalies, according to Scheme I., a and c, § 94, omitting 
the estimation of phosphoric acid, and consequently the 
addition of ferric chloride ; determine also the silica solu- 
ble in alkaline carbonate in the residue that is insoluble in 
hydrochloric acid above. 

Burnt clay may sometimes be profitably applied as a 
fertilizer, or an amendment. The examination of such a 
clay should be conducted in the same manner as described 
for burnt marl (§ 109,/); particular attention should be 
paid to the amount of alkalies soluble in water, and in 
cold and hot hydrochloric acid. 

The proportion of phosphoric acid is not usually any 
larger than in arable soils. 



§ 112. FAEM-YARD MANURE. 213 

CHAPTER YI. 

FERTILIZERS. 

T. 

PRODUCTS OF THE FARM-YARD. 

FARM-YARD MANURE. 

112. In the examination of farm-yard manure, tlie part 
soluble in water, and that which is insoluble in this agent, 
should each bo examined by itself, for it is important to 
know the relative proportion and composition of these two 
portions. 

To procure a sample of the manure, take several small 
portions from different parts of the pile, mix them all 
carefully together, breaking up the lumps while working 
the mass over, and preserve 3-4 kilos, for examination. 

a. Water.— Dry 1000 grms. of this in the drying- 
chamber, powder the residue as much as possible, or cut 
it up with shears, weigh the whole, dry about 50 grms., 
accurately weighed, at 100° C, and calcidate the loss of 
weight for the whole 1000 grms. Grind this dried sub- 
stance to a powder in a steel mill. 

b. Organic matter.— Ignite 6-8 grms. of this powder 
with the usual precautions, including the determination 
of carbonic acid and coal (§ 91). 

c. Carbonic acid,— Determine this in 5 grms. of the 
powder (§ 60). 

d. Nitrogen. — Determine this in 1 grm. of the powder. 
The small amount of nitric acid in the manure will be al- 
most completely converted into ammonia during the com- 
bustion, in the presence of so large a proportion of car- 
bonaceous orcranic matter. The nitrogen in the amnionic 



214 § 11^- FEETILIZEES. 

carbonate, that is volatilized during the process of dry- 
ing, and which is determined in the aqueous extract of a 
portion of the original manure, should be added to that 
obtained by combustion with soda-lime, in order to get 
the total nitrogen. 

e. Ammonia. — Determine this by the distillation of 
15-20 grms. of the dried and ground manure, with 1 grm. 
of freshly ignited magnesia, and water, and the estimation 
of the ammonia in the distillate by titration (§ 47, c). 

/. Sulplmr and sulptinric acid, — Determine total sul- 
phur in the manure by fusion of 3-4 grms. of the powder 
with potassic nitrate (§ 92). 

g. Aqueous extract of the manure. — Pour 3000 c.c. of 
water over a second portion of 1000 grms. of the fresh 
manure, mix the whole well together, let the mixture 
stand quietly several hours, and decant the supernatant 
liquid. In order to wash the residue Avithout using too 
much water, put it in a large funnel, which is stopped in 
the throat with asbestus, and below with a cork, press it 
down, pour water over it, and work the whole over gently 
with a pestle ; after a time, remove the cork, and let the 
liquid run off, and repeat the operation until the water 
that passes away is almost colorless. Reserve the residue 
in the funnel for further treatment. 

Filter the w^hole quantity of the liquid with which the 
fresh manure was treated through linen, make the volume 
of the filtrate and washings up to 6000 c.c, and, if neces- 
sary, filter again through paper. 

1. Ammonic salts. — ^Determine volatile ammonic salts 
(amnionic carbonate) in 300-600 c.c. of the aqueous ex- 
tract, by distilling off about "l^ of it in the proper appa- 
ratus (§ 47), without adding any alkali, and titrate the 
distillate with the standard sodic solution as usual. 

Determine non-volatile ammonic salts by adding 1-2 
grms. of freshly ignited magnesia, or 10-15 c.c. of milk of 



§ 112. FARM- YARD MANURE. 215 

lime to the remainder of the liquid in the retort, distilling 
off 'I3 of the water, collecting the ammonia in the usual 
manner, and titrating the distillate. 

The total amount of ammonia in the aqueous extract 
may be determined also by SchlOssing's method ; evapo- 
rate 200 c.c. of the liquid down to 50 c.c. after adding a 
slight excess of hydrochloric acid, and proceed with this 
concentrated solution in the usual manner (§ 47, h). 

2. Nitric acid* — To determine this in the aqueous ex- 
tract, evaporate 500 c.c. down to a small bulk, and pro- 
ceed with this concentrated solution according to SchlOss- 
ing's method (§ 62, a). 

3. Total amount of dry substance in solution.— Evap- 
orate the remainder of the extract to dryness in a weighed 
platinum dish, on the water-bath, and determine the total 
amount of matters in solution. 

4. Organic matter. — Ignite 3-4 grms. of this residue, 
to determine organic and inorganic matter (§ 91), and 
determine carbonic acid and chlorine in the ash (§ 60, e). 

5. Carbonic acid. — Determine this in 2-3 grms. of the 
residue obtained in 3 (§ 60). 

6. Nitrogen. — Determine this in 1 grm. of the residue 
obtained in 3, by combustion with soda-lime (§ 85). 

7. Chlorine. — This may be partially volatilized in the 
process of incineration ; an accurate estimation of it, there- 
fore, requires its determination in a portion of the aqueous 
extract itself. 100 c.c. of this may be taken, or 0.5-1 
grm. of the residue obtained in 3, dissolved in water. 
Add nitric acid to the solution, in slight excess, and pre- 
cipitate chlorine with argentic nitrate ; treat the j^recipi- 
tate as directed for the case in which much organic matter 
was present in the solution (§ 63). 

Instead of following this course, a small portion of the 
residue obtained in 3 may be fused with potassic nitrate 
before precipitation with argentic nitrate (§ 92). 



216 § 11'^- FERTILIZERS. 

8. Ferric oxide, etc .—Ignite the remainder of the 
residue obtained in 3, dissolve the ash in hydrochloric 
acid, eliminate silica by evaporation to dryness, and exam- 
ine the filtrate from the silicic acid according to Scheme 
I, § 94. 

h. The total residue, insoluble in water, obtained in ^, 
is dried in the steam-chamber, exposed to the air 24 
hours, and weighed in this air-dried condition ; then cut 
up the fibrous parts of it with the shears, and grind the 
whole to a fine powder in the porcelain mortar or steel mill. 

1. Water. — In 10 grms. of this powder determine hy- 
groscopic water by heating to 110° C. 

2. Organic matter. — Ignite the dry residue obtained 
in a^ and determine the loss (§ 91), and determine car- 
bonic acid and chlorine, if desired, in the ash. 

3. Nitrogen. — To determine the nitrogen in undecom- 
posed organic matter in the manure, a part of which might 
be insoluble in w^ater, and hence found here, ignite 1-2 
grms. of the powder with a considerable proportion of 
soda-lime (§ 85). 

4. Ferric oxide, etc. — Ignite 30-40 grms. of the 
powdered insoluble residue in a platinum dish, and in 
3-6 grms. of the properly prepared ash (§ 123, c), accord- 
ing to the proportion of sand present, eliminate silica and 
sand, and analyze the remainder according to Scheme I. 
or 11. 



] 13. URIXE. 



217 



i. Analyses of farm-yard manure by Yoelcker. 



Fresh. 



Water 

Soluble org-:vnic matter^ 

Mineral matter sohiljle in water 

Silica (soluble) 0.337 

Calcic phosphate, 3CaP04 ;0.299 

Lime 0.006 

Magnesia |0.011 

Potassa . 573 

Soda 0.051 

Sodic chloride i0.030 

Sulphuric acid «0.055 

Carbonic acid (and loss; 0.218 



Insolulile orij^anic matter^ 

Mineral matters insoluble in water 

Silica (soluble) 

Silica (insoluble, and sand).. 

Ferric oxide and alumina. . . . 



0.9G4 
0.418 

Lime jl.120 

Magnesia ^0.1-43 

Potassa 10.099 

0.019 
0.061 
0.178 
0.484 



Soda., 

Sulphuric acid 

Phosphoric acid 

Carbonic acid (and loss). 



'Contains nitroc-en. 



Free ammonia 

Ammoniacal salts. 



66.1 

!.48 



Rotted. 



1.54 



25.76 



4.05 



100.00 

0.149 
0.494 
0.340 

0.880 



1.424 
1.010 
0.673 
1.667 
0.091 
0.045 
0.038 
0.063 
0.274 
1.295 



.5.42 
3.71 



0.47 
12.82 



6.58 



100.00 

0.297 
0.309 
0.046 
0.057 



FRESH ANIMAL EXCREMENTS. 
URINE. 



113. The following method is designed more particu- 
larly for the analysis of the urine of herbivorous animals, 
but it may be applied in the examination of that of carniv- 
orous animals and man, also. 

a. Specific Gravity, — Determine this in the usual man- 
ner by comparing the weights of equaf volumes of the 
urine and of water (§ 34), or with the urometer, a species 
of hydrometer constructed expressly for this purpose; 
IQ 



218 § 113' FEKTILIZEES. 

when this instrument is used, all foam must be carefully 
removed from tlie surface of the liquid, by filter paper. 

A diiference of 4'^ C. in the temperature of the liquid 
usually makes a difference of about 1° in the reading of 
the urometer. 

The specific gravity of urine ranges between 1.01 and 
1.04. 

h. Total amount of dry substance in solution.— De- 
termine this by evaporating a weighed quantity in a cur- 
rent of dry hydrogen in such a manner as to estimate the 
ammonia that is expelled at the same time (§ 90, d). Take 
4-6 c.c. of the urine, accurately Aveighed. The evapora- 
tion to dryness is completed in 4-5 hours. 

In human urine, that has an acid reaction due to acid 
sodic phosphate, the ammonia may be assumed to have 
been derived from urea, and by multiplying the amount 
of it by 1.765, the corresponding amount of urea will be 
obtained. But in the urine of herbivorous animals the 
ammonia resulting from this decomposition must be esti- 
mated by the diflference between the ammonia set free on 
evaporation to dryness, and that found in the urine by di- 
rect determination. Generally, however, these quantities 
of ammonia are very small, and can be left out of consid- 
eration. 

The non-volatile matter in this residue left on evapora- 
tion is determined by evaporating a fresh quantity of 
100 c.c. of the urine in a platinum dish, and igniting the 
residue (§ 91, 1) ; detennine carbonic acid in the ash in 
the usual manner. 

e. Carbonic acid (free and combined). — Determine this 
in two portions of 100 c.c. of the fresh urine. To one 
portion add baric chloride containing ammonia in excess, 
and to the other baric chloride alone ; heat both mixtures 
nearly to boiling, collect the precipitates on dried and 
weighed filters, wash them, and dry them at 100°, weigh, 



§ 113. UMXE. 219 

and determine carbonic acid in 1-2 grms. of each precipi- 
tate in the usual manner; the first jn-ecipitate contains the 
total carbonic acid, the second only tlie combined. 

d. NitrOgCH. — Tlie residue lef*fc in the boat in h may bo 
used for the determination of nitrogen, or another portion 
of 5-10 c.c. of the urine may be acidified witli oxalic acid, 
mixed with ignited gypsum, and evaporated to dryness. 
In the former case this second residue will contain only so 
much of the nitrogen as was not expelled in the form of 
ammonia during the desiccation ; in the latter, the oxalic 
acid will prevent the escape of any nitrogen as ammonia. 
The dry substance may be completely rinsed off the sides 
of the dish with some of the soda-lime used in the com- 
bustion. 

Or, this method of Voit may be used. Weigh out 
about 5 c.c. of the urine, mix it in a shallow dish with 
a suflticient quantity of fine quartz sand to absorb it all, 
put the dish under the receiver of an air-pump, and ex- 
haust the air; the whole becomes quite dry in a few hours 
and may be pulverized easily, and completely loosened 
from the sides of the dish and mixed with the soda-lime. 

The combustion may be performed in a short combus- 
tion-tube and very rapidly, without fear of losing any of 
the ammonia. 

e. Actual ammonia. — Determine this by Schlossing's 
method in 20 c.c. of the urine, after filtration to remove 
slimy or sedimentary matters (§ 47, l>). In the fresh urine 
of horned cattle, the actual ammonia does not amount to 
more than 0.009-0.01" |„, but in human urine it ranges as 
high as 0.078 to 0. 143" t 

/. Complete analysis of the ash.— Evaporate 200-500 
grms. of the urine to dryness, incinerate the residue, and 
examine the ash as directed in Scheme IV., § 94. The ash 
of the urine of herbivorous animals is poor in alkaline 
earths, and 8-10 grms. will be required for their determi- 



220 § 113. FEIITILIZEIIS. 

nation. In the urine of ruminants, phosplioric acid U 
found in hardly determinable quantity, Avbile in that of 
swine and often of calves, it is present in larger quantity, 
and should be estimated. 

(/. (Chlorine and urea. — These are determined with tlie 
aid of the standard solution of mercuric nitrate. The 
urine must first be freed from phosphoric and hippuric 
acids. 

Acidify 200 c.c. with nitric acid, boil the mixture to ex- 
pel the carbonic acid, neutralize the nitric acid with 
freshly ignited magnesia, and cool the liquid to the tem- 
perature of the room, by immersing the flask in cold wa- 
ter ; transfer the liquid to a graduated cylinder, rinse the 
flask into the cylinder and bring the volume of its con- 
tents to 220 c.c; add 80 c.c. of an aqueous solution of fer- 
ric nitrate of such a degree of concentration that, with 
this quantity of the solution added, the salt will be slightly 
in excess ; the excess may be recognized by a weak reac- 
tion of the solution on a slip of filter paper soaked in a 
dilute solution of potassic ferrocyanide ; too large an ex- 
cess of the ferric salt will be indicated by a re-solution of 
the precipitate that was formed at first, on its addition ; 
filter the liquid immediately through a large, dry, ribbed 
filter, and to 150 c.c. of the filtrate add 50 c.c. of a solu- 
tion of baryta mixed with a little calcined magnesia, filter 
a<^ain, and for each determination of sodic chloride and 
urea take 15 c.c. of this filtrate, corresponding to 9 c.c. of 
urine. 

1. Chlorine (common salt). — Acidify exactly 15 c.c. of 
the liquid with a drop of nitric acid, and allow the stand- 
ard solution of mercuric nitrate to flow in from the burette, 
with constant stirring until a permanent turbidity ap- 
pears. A mere opalescent appearance of the liquid, which 
may be presented even in the beginning, is easily distin- 
guished from the cloudy turbidity which is the real indica- 
tion of saturation. 



§ 113. URINE. 221 

Estimate the amount of sodic chlorine or of chlorine on 
the basis of the standard of the solution already determ- 
ined (§ 86). 

2. Urea. — In a second portion of 15 c.c. of the liquid, 
proceed to determine urea with the same standard solution 
(§ 86). Subtract from the total amount of standard so- 
lution required the amount used in 1, and also make the 
correction required for dilution of the solution. 

h. Hippillic acid. — Evaporate 200 c.c. of the urine 
down to 50 c.c, and precipitate the acid as directed in § 
76. It may be well to first digest the urine with animal 
charcoal in the proportion of 2 grms. of charcoal to 10 c. 
c. of the liquid, in order to decolorize it. 

There are usually only traces of urio acid i:i the urine 
of herbivora, and it need not be estimated ; but in the 
urine of carnivora, the proportion of uric acid generally 
exceeds that of the hippuric. 

According to the process of Meissner and Shepard, for 
separating these two acids, evaporate the urine until it be- 
gins to crystallize, add so much absolute alcohol to the hot 
liquid that a further addition causes no more precipitation, 
I'jt the mixture cool, and filter it ; the best absolute alcohol 
must be used, and it must not bo spared, else succinic 
acid may remain in solution with the hippuric and cause 
trouble. Evaporate the alcoholic solution, at first in a 
fiask on the water-bath, until all the alcohol and the water 
are expelled and only a brown syrup remains, that solidi- 
fies to a crystalline mass on cooling ; extract this mass, 
while yet warm and liquid, with ether and a few drops of 
hydrochloric acid added after the ether, agitate the mix- 
ture violently, and repeat the process two or three times 
vvdth fresh portions of ether. If the alcohol and water 
were not carefully removed in the preceding evaporation, 
some of the urea will pass into this etherial solution. 

Collect all the etherial extracts, distil ofi* most of the 
ether, and let the rest evaporate spontaneously in the air. 



222 § 113. FERTILIZEPwS. 

Hippiiric acid appears then in the form of handsome 
crystals. If the crystals are not colorless, or they are not 
readily formed, dilute the residue, left by the evaporation 
of the ether, with water, boil the mixture with lime-wa- 
ter, filter, concentrate the colorless filtrate, and precipitate 
the hippuric acid by hydrochloric acid in excess. 

i. Phosphoric acid. — 1. This may be determmed di- 
rectly in tlie urine, Avith the standard uranic solution. 
Filter -the urine, if necessary, add 5 c.c. of sodic acetate 
to 50 c.c. of the filtrate, and titrate the mixture with 
uranic acetate as usual (§ Gl, c). 

2. To obtain a more accurate determination, add the 
magnesia mixture to 50 c.c. of the clear urine, collect and 
wash the precipitate in the usual manner, dissolve it, with- 
out drying, in acetic acid in not too great excess, di- 
lute the solution to 50 c.c. with water, add 5 c.c. of the 
solution of sodic acetate, and titrate as before. Avith the 
uranic solution (§ 61, c). 

8. To determine the phosphoric acid that is combined 
Avith alkaline earths only, to 100-200 c.c. of the urine, ac- 
cording to its strength, add ammonia until alkaline reac- 
tion ensues, let the mixture stand 12 hours, and collect 
and treat the precipitate in the manner described in 2. 
In another precisely equal quantity of urine, the precij^i- 
tate by ammonia is ignited and weighed ; the amount of 
magnesic pyrophosphate in this mixture may be estimated 
by multiplying the amount of phosphoric acid in it, as de- 
termined above, by 2.1831, subtracting the sum of the 
phosphates from this product, and multiplying the re- 
mainder by 2.5227. If it is desired to determine lime and 
magnesia directly, dissoh^e the mixture of the phosphates, 
obtained above by precipitation Avith anmionia, without 
drying it, in as small a quantity of acetic acid as possible, 
precipitate the lime by ammonic oxalate, and the mag- 
nesia as phosphate again by excess of ammonia. 



§ 114. SOLID EXCREMENTS. 223 

Tc, Sulphuric acid, — Heat 50-100 c.c. of the urine, add 
some nitric acid, and then baric chloride in slight excess 
(§ 59). 

I. Sulphur. — To determine total sulphur, mix 50 c.c. of 
the urine in a silver crucible with solid caustic potash and 
a little saltpetre ; , evaporate the mixture cautiously to 
dryness, ignite the residue strongly until it is quite white, 
exhaust it with water, and determine sulphuric acid in the 
filtered solution, in the usual manner. 

m. Carbon and Hydrogen. — Absorb 10 c.c. of the urine 
by fine quartz sand that has been previously boiled with 
acid, washed, and ignited, dry the mixture, and burn it 
with plumbic chromate. (See Fresenius's Quantitative 
Analysis.) 

SOLID EXCREMENTS. 

111. The solid excrements of the herbivora are exam- 
ined by almost precisely the same methods as are given 
for the analysis of fodder (§ 129). 

In the determination of woody fibre, owing to the pres- 
ence of resinous matters it is often necessary to boil the 
substance with alcohol before treating it with dilute acid 
and alkali. 

Microscopic examinations are often useful in the exami- 
nation of these excrements, in order to ascertain what 
parts of the plants, that were consumed as fodder, remain 
undigested. For this purpose, it is well to knead a por- 
tion of the substance in a linen bag under cold water un- 
til the latter is no longer made turbid. Starch, crystals 
of difficultly soluble salts, and grains of sand, may be 
looked for in the sediment deposited from the water used 
in washing, after long standing, while sugar, gums, lactic 
acid, etc., may be sought for in the solution ; the residue 
in the bag may be examined with the microscope, with or 
without previous boiling with alcohol to remove resinous 
matters. 



224 § 115. FERTILIZERS. 

II. 

COMMERCIAL CONCENTRATED MANURES. 



115. The determinations of phosphoric acid, potassa, and 
nitrogen, are the most important in the examination of 
these manures. 

a. The method first recommended by Pincus for esti- 
mating phosphor la acid by means of a standard solution 
of uranic acetate can be applied in the analysis of guanos, 
bone-meal, bone-black, bone-ash, and most of the super- 
phosphates, so long as but little ferric oxide or alumina is 
present. The method deserves to be generally followed, 
for it is quickly executed and sufficiently accurate, and 
because it is desirable that all estimations of phosj)horic 
acid, in the numerous forms in which it is presented to the 
public; should be made according to a common plan. 

The preparation of the standard solution and the man- 
ner of conducting the analysis have been already describ- 
ed (§ 61, c). 

For the determination, 50 c.c. of the solution to be test- 
ed are generally taken, and 10 c.c. of the solution of sodic 
acetate added. If the quantity of the precipitate that is 
formed on the addition of this reagent and boiling is quite 
small, it may be filtered out, washed, dried, and ignited ; 
the residue may be regarded as ferric phosphate, FePO^, 
containing 47.02"! „ of phosphoric acid (P^O J. The volu- 
metric process is carried out with the filtrate from this 
precipitate. If the precipitate of ferric pliosphate is not 
slight, a gravimetrical process is safer (§ 93, H). 

The vo'lumetric process, under suitable circumstances, 
gives results that are within 1 mgr. of the truth. 



§ 115. COMIMERCIAL CONCENTIIATED MxVNURES. 225 

In case a, large quantity of phosplioric acid is ])resGnt, 
or much free acid, 10 c.c. of tlie acetate may not be suf- 
ficient to saturate all this acid with soda. The brown 
color will appear, then, before all the phosphoric acid is 
precipitated; but it is diffused through the entire drop, 
and does not present a well-defined brovrn zone wliere the 
drop of the test solution and of the ferrocyanide come to- 
gether; in this case add 5 c.c. more of sodic acetate, and 
it will be found tliat, in case free mineral acid was present, 
more of the uranic solution must be added before the 
brown color appears. In order to be sure in regard to 
this matter, it will always be well, after having reached 
the point of saturation, to add 5 c.c. more of sodic acetate, 
heat the mixture to boiling, and test a drop of the solu- 
tion with the ferrocyanide. If a brown color appears, the 
result first obtained was correct. Even 30 c.c. of sodic 
acetate may be added without sensibly impairing the 
accuracy of the work. 

h. The examination for potassa may be conducted ac- 
cording to either of the methods described in § 93, G. 
The third method, in v/hicli platinic chloride is used to 
separate potassa from the alkaline earths, is more particu- 
larly applicable in the examination of the native potash 
salts, of which such extensive beds have been discovered 
in Germany, and from which large quantities are taken for 
agricultural purposes. 

c. The determination of the nitrogen, is always made by 
combustion with soda-lime (§ 85). 

d. Fresenius {Quantitative Chemlsche Analyse^ 894) 
gives the following good plan for stating the results of the 
analysis of a superphosphate ; a similar plan can be fol- 
lowed, with such variations as may be necessary in each 
particular case, in stating the result of the analysis of any 
commercial fertilizer. 



10* 



220 



115. FERTILIZERS. 



Easily 
soluble 

in 
water. 

Diffi- 
cultly 
soluble 

in 
water. 



united 

with 

the P2O5 



Phosphoric acid, H3PO4 
Lime 

-) Mai,aiesia 
I Ferric oxide 
[ Potassa 

r 

Calcic sulphate 
(CaS04, 2aq.) 

r Phosphoric acid 
Soluble J Lime | united 

in acids, j Magnesia V Avith 

[ Ferric oxide ) the acid 

Volatile matter, expelled on ig 

nition 

Water expelled at 100° C 



16.15|eont. PsOsLauhyd] 
0.5 



43.00 

2.19 
1.01 

3.49 



cont. P2O5 [anhyd] 



6.51 
39. 15 I 
100.00 



contain'jr nitrogen 



P.O5 

11.7 



3.19 



0.41 
13.89 0.41 



TAPvIFF OF PPJCES OF COMMERCIAL FERTILIZERS. 



e. In 1857, A. Stuckhardt, of Tharand, published a 
tariff of prices of commercial fertilizers, with the aid of 
which, in a very simple manner, the cost of the manure 
could be compared with its real value ; in this tariff, the 
estimation of the money value of each of the three im- 
portant constituents of these fertilizers in general, was 
based upon the price that would have to be paid for it in 
other and also commercial forms, containing a known and 
often guaranteed proportion of the substance. The per 
cent composition of a fertilizer being known, the pur- 
chaser could then tell, on consulting the tariff, whether he 
was required to pay any more for the number of pounds of 
nitrogen or phosphoric acid in 100 pounds of the article 
he was buying, than he would have to pay for the same 
number of pounds of nitrogen in the form of sulphate of 
ammonia, from the gas-works, for example, or of phos- 
phoric acid in the bone-black of the sugar refiners. 

A greatly improved form of this tariff, which was put 
out by Stockhardt in 1806 ( Chemische Ackersmanji, 1866, 



115. TAKIFP OF PRICES OF FERTILIZERS. 



227 



226), is given below, with the prices estimated i?i r/old ^cr 
pound. 

Tlie editor greatly regrets that he has not had the time 
or the opportunity to make a careful examination of the 
various forms in which nitrogen, phosphoric acid, and pot- 
ash, are to be had in this country, so that this tariff might 
be conformed therewith, and answer the same purpose for 
the American farmer that the original one does for the 
farmers throughout Germany. But, nevertlieless, the 
values allowed for these three substances in the tariff as 
it stands are not far out of the way. Prof Johnson {He- 
port to the Secretary of the State Board of Agriculture, 
0)1 Commercial Manures^ April., 1869) gives the following 
values 1)1 gold: potash, 4 cents; soluble phosphoric acid, 
12^ cents; insoluble, 44- cents; nitrogen, 17 cents. The 
mean of the four values of nitrogen in Stockhardt's tariff 
is 17.9 cents. 

Prof. Johnson says very truly in the same report, " The 
farmer will not often err in refusing to lay out his money 
for any article whose cost much exceeds the calculated 
value," with reference to his own tariff; and the same may 
as well be said of the scale of prices adopted in this work. 



Form in Avhicli tlie substance exists in tlie fertilizer. 

Phosphoric acid, soluble in water, as in superphosphate 

" " in Peruvian guano 

" " in steamed bones finely ground, in rape cake, 

poudrette, etc 

" " in Baker guano 

" " in coarse bone meal, fresli human urine, etc.. 
" " in coarse broken bones, fresh human excre- 
ments, stable manure, etc 

Potash, as potassic sulphate 

" as potassic chloride and in other forms 

Nitrogen, easily soluble, or in compounds that are readily de- 
composed, as ammonia, nitrates, dried blood, 

meat, urea, etc 

" in finest bone meal, poudrette, etc 

_" in coarse bone meal, rape meal, horn meal, wool dust, 

fresh human urine, etc 

" in coarse broken bones, horn shavings, woolen rags, 
fresh human excrements, stable manure, etc 



Price 
ra) lb. 



in gold. 

% .12^ 
.10 

.083^ 

.07 

MY, 

MY 



.22 

.193^ 

.16K 
.13^ 



228 § 116. FERTILIZERS. 

According to this tariff, tlie mouey value of 100 pounds of tlie super- 
pliospliate whose composition is given above, would be estimated as 
follows : 

11.7 lbs. soluble phosphoric acid @ 12>2 cts. $1.46 

3.19 " insoluble " " " 1% " .32 

.41 " nitrogen " 19>2 " .08 

$1.86 

The value of a ton of 2000 pounds, at the same rate, would be $37.20 
in gold. 

BONE-MEAL. 

116i Bone-meal, as found in commerce, is prepared 
either from nearly or quite fresh bones, from bones that 
have been exposed to the air for some time, or from those 
that have been steamed or boiled ; the first kind contains 
much fat and gelatine, and is usually quite coarse ; the 
third kind has lost nearly all its fot and much of its gela- 
tine, and is quite fine ; while the second occupies a position 
between the other two in all respects. 

a. Watert — ^Desiccate about 5 grms., if of the common 
kmds of steamed bone-meal, at 100°. 

h. IVon-VOlatliC matter. — Ignite the dried residue in a 
and treat the ash with amnionic carbonate, to restore car- 
bonic acid that was expelled by heat (§ 91, d). 

c. JVitrog^Ofle — Burn 0.5-0.8 grms. of the finely jDowder- 
ed meal with soda-lime (§ 85). . 

d. Phosphoric acid. — Dissolve 3-4 grms. of the ash 
obtained in b in as little nitric acid as possible, with the 
aid of heat; filter the solution into a 250 c.c. flask, wash 
the sandy insoluble residue, ignite, and weigh it. Fill the 
flask with distilled water up to the 250 c.c. mark, mix its 
contents well together, and determine ])hosphoric acid in 
50 c.c. of this solution, with the standard nranic solution 
(§ 115, a). In order to saturate the free acid, it will be well 
to add 20 c.c. of the sodic acetate. If a coarse, sj^lintery 



§ 116. BOXE-MEAL. 229 

bone-meal is under examination, a larger quantity, about 
50 grms., should be incinerated in order to get tlie ash for 
treatment with acid. 

e. Complete analysis of the asli. — Treat a portion of 
the solution obtained in d according to Scheme IV., § 91, 
taking 50-100 c.c. for a and the same for h. This exami- 
nation is, in general, unnecessary, if the only' object of the 
analysis is to determine the agricultural value of the 
article. 

/. Fat.— Exhaust a weiglied quantity of the finely pul- 
verized meal with ether, dry the residue at 125° C, and 
count the loss as fat (§ 87). 

g. Clelatilie. — The gelatinous substances may be esti- 
mated by the diiference between the total loss on ignition 
and the sum of the water and fat. 

A. Fineness of division of the meal. — The value of 

bone-meal depends not only upon its chemical composition, 
but also upon the fineness of the powder. 

To test the substance in this respect, it should be passed 
through sieves of different degrees of fineness; and it is 
important that all chemists should use sieves of the same 
kind, so that the results obtained by difierent persons can 
be compared Avith each other. 

Wolff recommends the use of the three finest sieves of 
the set made by IIugershofF, in Leipzig, the first of which 
(I) has 1089 meshes in a square centimetre, the second 
(It) 484 meshes, and the third (III) 256. The residue, 
tliat will not pass through the coarsest sieve, should be 
examined, in order to see whether it is made up largely 
of grains which would pass through a little coarser sieve 
still, or of large splinters. 

One bone meal of excellent quality, analyzed by Wolff, 
contained 60'|„ of No. I., 20"|„ of No. II., and 10°|„of 
No. III. 



230 § 117. FERTILIZERS. 

BONE-BLACK, BONE-ASH, PHOSPHORITE. 

117, A. J^ one-black, after it hns been used by the sugar 
refiners, usually comes into the market as a manure. Pul- 
verize 30-40 grms. of it for examination. 

a. Water,— Desiccate 3-4 grms. for a considerable time 
at 150° C. 

b. Non-volatile matter,— Ignite the dried substance 
obtained in t/, and treat the residue Avith ammonic car- 
bonate, to restore carbonic acid expelled during the igni- 
tion (§ 91). 

c. Carbonic acid, — Estimate this in 3 grms. (§ 60). 

d. Nitrogen,— Burn 0.5 to 0.8 grm. with soda-lime 
(§ 85). 

e. Phosphoric acid, etc, — Digest the contents of the 
flask in c, after adding a little more nitric acid, several 
hours on the water-bath ; filter the liquid into a 250 c.c. 
flask, wash the residue with hot water, dry it at 150°, 
weigh, ignite, and weigh again. The loss on ignition gives 
approximately the amount of charcoal, and the residue 
left after ignition is to be considered as sand, though it 
may be tested with nitric acid to see whether any more 
is soluble. 

Dilute the contents of the flask to 250 c.c, mix all parts 
of the solution Avell together, and determine phosphoric 
acid in 50 c.c. with the uranic solution (§ 115, a). 

f. Complete analysis of the ash. — Treat a portion of 
the solution obtained in e, or a solution obtained in tlie 
same manner, as directed in Scheme IV., § 94, taking 100 
c.c. for a and the same for b. 

(/. Chlorine may be determined in a portion of the so- 
lution obtained in e, by precipitation with argentic ni- 
trate (§ 63). 

A. Calcic hydrate, — It is sometimes desirable to de- 
termine this in the bone-black. Moisten a portion of the 



§ 117, BONE-BLACK, BONE-ASII, PIIOSPIIOEITE. 231 

original substance with a solution of amnionic carbonate, 
evaporate the mixture very carefully to dryness in a cov- 
ered crucible, repeat the operation several times, and ig- 
nite, finally, to a dull red heat, not strong enough to burn 
the coal. Determine carbonic acid in this residue ; the 
difference between the quantity found here and in c repre- 
sents an equivalent quantity of cnlcic hydrate or caustic 
lime, CaO, H,0. 

B. Bone-ash should be treated as directed for the ash 
of bone-meal, Avith the addition of determinations of 
moisture and of carbonic acid, for the purpose of estimat- 
ing the calcic carbonate. 

C. Phosphorite, coprolites. — Phosphorite, nnd other 
minerals containing phosphoric acid, are usually mixed 
with oxides of iron and alumina to such an extent that 
the acid cannot be determined volumetrically. 

a. Phosphoric acid. — To determine this alone, Freseni- 
us gives the following directions. {Fresenius^s Zeitschrift, 
6, 404). 

Heat about 0.5 grm. of the finely pulverized mineral in 
a small flask about an hour on the water-bath, with 8-10 
c.c. of concentrated (fuming) hydrochloric acid, and 
evaporate the mixture to dryness in the usual manner for 
eliminating silica (§ 58, a, 1 ) ; moisten the residue with 2 
c.c. of hydrochloric acid, add, after a short time, 10 c.c. 
of concentrated nitric acid (Sp. Gr. 1.2), dilute with 
Avater, filter and Avasli the insoluble residue ; evaporate the 
filtrate and washings almost to dryness, dissolve the resi- 
due in 5 c.c. of nitric acid, transfer the solution to a beak- 
er, rinse out the evaporating dish Avith a little water, and 
then with the solution of ammonic molybdate ; add, in 
all, 150-200 c.c. of this reagent, and proceed with the 
elimination of the acid as directed in § 61, h, 

h. Complete analysis. — ^Digest 5-10 grms. of the Avell- 
pulverized mineral with hydrochloric acid, filter out the 



232 § 118. FEKTILIZEES. 

insoluble substance, dry it, boil it repeatedly with sodic 
carbonate, to dissolve out the silicic acid (§ 58, a, 2), and 
treat this insoluble residue with 6-8 thnes its weight of 
sulphuric acid to decompose the clay, as directed under 
soil analysis (§ 102). Evaporate the solution in hydro- 
chloric acid obtained above to dryness, and eliminate and 
weigh tlie silica (§ 58, «, 1), and examine the filtrate from 
tliG silica, as directed in Scheme L, except that manganese 
ueed not be determined, unless a qualitative test reveals 
its presence in notable quantity. 

GUANO. 

118. A. Peruvian or other conmoniacal giionos. — 
Pulverize 200-500 grms. until the whole will pass through 
a tolerably fine sieve. 

a. Water. — Estimate this in 1-2 grms. in such a manner 
as to collect the ammonia that is expelled at the same 
tim3 by the heat (§ 90, d). The amount of ammonia 
given off is usually from 1-2" |^ of the weight of the guano. 

h. Non-volatile matters. — Ignite 6-8 grms. carefully in 
a platinuin crucible (§ 91). 

c. Nitrogen. — Burn 0.5 grm. with soda-lime. The mix- 
ture should be made as quickly as possible in tlie tube, 
and the bulbed tube attached immediately, to prevent any 
loss of ammonia (§ 85, h). 

d. Actual ammonia. — Determine this in 1 grm. by 
Sciilossing's process (§ 47, ^>'). 

e. Phosplioric acid, etc. — Digest the asli obtained in h 
Avith nitric acid, filter out the ^and^ wash, ignite, and 
weigh it, and dilute tlie filtrate to 250 c.c. 

Determine phosphoric acid in 50 c.c. of this filtrate, by 
tlie volumetric method (§ 115, ci). 

For another method of estimating phosphoric acid alone, 
mix 1 part of guano (1-2 grms.) with 1 part of sodic car- 



§ 118. auANO. 233 

bonate mid 1 of nitre, fuso the mixture carefully, dissolve 
the residue in water, and evaporate tlie solution to dryness 
on the water-bath ; treat this residue with hydrochloric acid 
and water, as in eliminating silicic acid (§ 58, «, 1) ; filter, 
add ammonia to the filtrate until it is in slight excess, then 
acetic acid until the calcic phosphate precipitated by the 
ammonia is dissolved ; and then, without filtering out the 
small amount of ferric phosphate, determine phosphoric 
acid by the A^olumetric method. (Fresenius.) 

/. Complete tinalysis. — Treat a portion of the solution 
obtained in c, or one obtained in like manner, after elimi- 
nation of silicic acid, according to Scheme lY., § 94. 

f/. SolwMllty in water. — Heat 10 grms. of the powdered 
guano with 200 c.c. of water, filter at once through a 
weighed filter, wash tlie contents of the filter with hot 
water, as long as the water has any yellow color and 
leaves a residue when evaporated ; dry and weigh the in- 
soluble residue. Subtract the sum of the water and the 
insoluble substance from the total weight of the guano, 
and the remainder will be the soluble matter ; and, if the 
insoluble residue is ignited and the ash weighed and sub- 
tracted from the total amount of ash, the amount of solu- 
ble non-volatile matters will be given by the remainder. 
(Fresenius.) 

h. Uric acid, — Digest the part of the gunno that is in- 
soluble in water with a weak solution of sodic hydrate ; 
filter the mixture, precipitate the uric acid in the filtrate 
with hydrochloric acid, and proceed as directed in § 75, 
with the washing of the precipitate. 

^. Oxalic acids — Expel the carbonic acid from a weigh- 
ed portion of the guano with sulphuric acid, neutralize 
the excess of acid with sodic hydrate entirely free from 
carbonic acid, and estimate oxalic acid with sulphuric acid 
and manganic binoxide (§ 69). 

k Marks of a good Peruvian guano.— It forms a loose, 



23 i § 119. FERTILIZERS. 

yellowisli-broAvn powder mixed with soft lumps of various 
sizes, which, when broken, exhibit white veins on the 
fractured surface, or sometimes a foliated crystalline ap- 
pearance. 

If a small quantity is heated with a few drops of dilute 
nitric acid and the mixture is evaporated to dryness at a 
gentle heat, a fine, purple-red colored residue is left, indi- 
cating the presence of uric acid (§ 75). 

It gives a good reaction for ammonia with so die hydrate 
or lime. 

By digestion with water, about half is dissolved, form- 
ing a dark-yellow solution; if the guano is poor, a light- 
yellow solution is obtained. This solution gives the usual 
reactions for ammonia, lime, magnesia, and sulphuric acid. 

It loses GO-70"! ^ when ignited, and leaves a grayish- 
white ash that evolves but little carbonic acid when treat- 
ed with nitric acid, and leaves but from 1-3°| ^ of matters 
insoluble in acid, and contains 5-10" |„ of fixed alkaline 
salts. 

Baker guano, and other pliosphatk guanos. — These 
are examined in the same mannei* as the Peruvian guano, 
except that, since they contain but a very small propor- 
tion of nitrogen and alkaline salts, the determination of 
phosphoric acid alone answers for the estimation of their 
agricultural value. This may generally be made by the 
volumetric process. 

SUPERPHOSPHATES. 

119. These are generally mixtures of calcic sulphate, 
calcic chloride, tricalcic phosphate, ferric phosphate, 
monocalcic phos2:)liate, organic matters containing nitro- 
gen, coal and water. 

Mix the sample well together, breaking up all the lumps 
between the fingers or in the mortar. 

a. Water. — Desiccate 3-4 grms. for a considerable time 
at 150-160° C. (§ 90). 



§ 119. suPEEPnospnATES. 235 

h. Non-volatile matters. — Ignite the dry residue ob- 
t:uned in a (§ 91). 

c. Kitrogea. — This should be determined, in case the 
l)hosphate Avas prepared from Peruvian guano or bone- 
meal, or it is claimed that it contains nitrogenous matter. 
Ignite 0.5-1 grm. with soda-lime. 

d. Actual ammonia. — Determine this, if present, by 
Schlossing's process, in 1-2 grras. (§ 47, h). 

e. Phosphoric acid. — The value of a superphospliate 
depends chiefly upon the amount of phosphate that it con- 
tains that is soluble in water, and, when the article was 
prepared from bone-black, bone-ash, phosphorite, or Baker 
guano, the determination of soluble phosphate suffices for 
the estimation of its value. But when made from steamed 
bones, wholly or in part, there is commonly from 5-6" 1^ of 
insoluble phosphate which should be taken into account. 
It appears that sometimes the proportion of soluble j^hos- 
phate diminishes when the article is kept for a long time ; 
if, therefore, an unexpectedly small amount is found, a 
determination of the insoluble phosphate should be made 
also, in order to estimate fairly the value of the fertilizer. 

1. To estimate the soluble phosphate^ triturate 10 grms. 
of the well-mixed sample with 200-300 c.c. of water, ap- 
plying pressure enough with the pestle to break up the 
lumps, but not to pulverize the hard grains ; let the mix- 
ture stand some time, pour off the clear supernatant liquid 
through a filter, and repeat the exhaustion with water as 
long as an acid reaction is communicated to a fresh por- 
tion ; finally, put the whole insoluble residue on the filter, 
dry it at 100°, and weigh it; bring the volume of the 
aqueous extract to 1000 c.c. 

Determine phosphoric acid by the volumetric method 
in 100 c.c. of this solution, first precipitating and filtering 
out the ferric phosphate, if but a small quantity is formed, 
and dry and weigh this precipitate ; 47.02° \^ of it is phos- 



236 § 119. FERTILIZERS. 

phoiic acid. If the superphosphate was made from a 
phosphatic guano, this precipitate of ferric phosphate will 
generally be too large to allow an accurate volumetric 
estimation of phosphoric acid, and a gravimetrical method 
should be followed. (§ 93, 7Z) 

2. To estimate the insoluble phosphate^ treat 20 grms. 
of the substance with water to which 20 c.c. of nitric acid 
(Sp. Gr. = 1.4) have been added, and digest the mixture 
several hours on the water-bath. If a sufficient quantity 
of acid was added, the insoluble residue left after diges- 
tion can be plainly seen, when stirred up, to consist of 
nothing but heavy sand and particles of coal ; if tbe so- 
lution appears to be iucomplete, add 10 c.c. more of the 
acid and heat the mixture again several hours ; finally, 
filter the solution into a litre flask, and when the filtrate 
is cool, bring its volume up to 1000 c.c. ; determine phos- 
phoric acid by the volumetric method (§ 115, ci) in 50 c.c. 
of this solution, using 20 c.c. of sodic acetate. 

This residt gives the total amount of phosphoric acid 
in the superphosphate, and, as the soluble phosj^hate has 
already been determined, the amount of insoluble phos- 
phate is readily estimated. 

The insoluble residue of sand in this examination may 
be ignited and weighed. 

f. Complete aaalysISi — Examine the aqueous solution 
prepared above, if it is particularly desired to learn its 
composition, according to Scheme IV., § 9-1, taking 100 c.c. 
for c/, and 100 c.c. for h with previous treatment with 
sodic carbonate and potassic nitrate ; also determine chlo- 
rine in 50 c.c. of the solution, by precipitation with ar- 
gentic nitrate (§ 63). 

Or, for a more complete analysis, including the determi- 
nation of what is soluble in acid with what is soluble in 
water, examine the nitric-acid solution obtained in e ac- 
cording to Scheme IV., except in case the phosphate 
contains much organic matter, when it would be better to 



§ 120. GYPSUM. 237 

analyze a solution of the ash obtained in h^ in nitric acid. 
tinlphurl'c add and chlorine, however, must always be 
determined in the nitric-acid solntion of the original sub- 
stance. 

GYPSUAL 

120. a. Water. — Ignite 2 grms. of the finely pulverized 
gypsum gently. 

J). IllS©i5lble natters, — Digest 2 grms., likewise finely 
powdered, with very dilute hydrochloric acid, as long as 
anything appears to be dissolved, filter out the insoluble 
sand and clay, wash well with hot water, dry, ignite, and 
weigh the insoluble residue. 

c. Sulphuric acid, ferric oxide, lime, etc. — Divide 
the acid solution in two equal parts, and in one pre- 
cipitate sulphuric acid with baric chloride (§ 59), and 
in the other, after dilution with water and heating with 
a little concentrated nitric acid, precipitate ferric oxide 
and alumina, with ammonia in slightest possible excess 
(§ 51). Filter the precipitate out quickly, so as to 
avoid the precipitation of calcic sulphate in the alkaline 
solution, wash it well, and then weigh it after ignition. 
Immediately on filtering out this precipitate by ammonia, 
add ammonic oxalate^ in excess to the filtrate to 23re- 
cipitate the lime (§ 49, ^y), and estimate magnesia in the 
filtrate from the lime, in the usual way wdth hydric 
disodic phosphate (§ 50, h) 

d. If there is a considerable precipitation of ferric oxide 
by ammonia, some calcic sulphate is very liable to be 
mixed with it. In this case, it is better to boil about 
1.5 grms. of the finely powdered gypsum an hour with a 
solution of 6-8 grms. of pure sodic carbonate ; by this 
operation, if the gypsum was properly pulverized, it is 
completely converted into calcic carbonate. Filter, wash 
the contents of the filter well with hot water, and precipi- 



238 § 121. FERTILIZEKS. 

tate the sulphuric acid in the filtrate with baric chloride ; 
transfer the filter with its contents to a deep beaker, and 
dissolve the carbonate in dilute hydrochloric acid with 
the usual precautions, filter, wash well, dry, ignite, and 
weigh the residue of sand and clay. Determine lime and 
magnesia in the filtrate in the usual manner (§ 50, b). 

e. Alkalies. — To determine these in gypsum, boil 10 
grms. repeatedly with dilute hydrochloric acid, filter, and 
eliminate the alkalies as chlorides (§ 93, G.). 

y*. A determination of carhonic acid will furnish means 
of estimating the amount of calcic carbonate in the gyj^- 
sum ; take 5-10 grms. for the analysis {§ 60). 

SALT. POTASH COMPOUNDS. 

121, A. Salt. a. Water, — Gently ignite 3-4 grms., 
well pulverized, in a platinum crucible that is kept well 
covered, and carry the temperature finally to a dull red. 

h. Complete analysis, — Dissolve 10 grms. in hot water, 
filter the solution into a litre flask, and wash, dry, ignite, 
and weigh the insoluble residue. 

This residue consists mostly of sand and clay. If gyp- 
sum is contained in it, digest it with dilute hydrochloric 
acid as long as anything appeal^ to be dissolved, filter 
the solution, add ammonia in excess to the filtrate, filter 
out the precipitated ferric oxide and alumina, precipitate 
lime in the filtrate by aramonic oxalate, and sulphuric acid 
in the filtrate from the calcic oxalate by baric chloride 
after acidification with hydrochloric acid. 

Bring the volume of the aqueous solution of the salt, ob- 
tained above, to 1000 c.c, and determine lime and mag- 
nesia in 400 c.c. (§ 50, h)^ and chlorine in another portion 
by the volumetric process (§ 63, h). Dilute 300 c.c. with 
more water, acidify it with hydrochloric acid, and exam- 
ine the solution for sulphuric acid and the alkalies (§ 93, 



§ 122. CHILI SALTPETRE. 239 

E and G). The determination of potassa in common 
salt is generally unnecessary. 

B. Potassa salts. — Dissolve 10 grms. in hot water, and 
determine 2^otasm at once with platinic chloride in a por- 
tion of the solution (§ 93, G, 3). 

For the complete analysis, or the determination of 
water, proceed as directed for the analysis of salt. 

CHILI SALTPETRE. 

122. a. Water.— Desiccate 3 grms. at 110° C. 

h. Complete analysis. — Treat 20 grms. of the pulver- 
ized salt with hot water, filter the sokition into a litre 
flask, collect the insoluble residue on a dried and weighed 
filter, wash it well with hot water, dry it at 125° C, 
weigh it, and then ignite it at a low temperature, and 
weigh the ash. These results give the amount of insolu- 
ble sa)id and day, and, approximately, the organic matter. 

Bring the volume of the aqueous solution to 1000 c.c, 
determine sulphuric acid and chlorine in two portions of 
200 c.c. each, by precipitation with baric chloride (§ 59) 
and argentic nitrate (§ 63), and lime and magnesia in an- 
other portion of 500 c.c. (§ 50, h). 

c. Soda. — This may be estimated by the difference 
between the total amount of substance taken, and the 
sum of the acids, water, organic matter, and the other 
bases ; or it may be estimated by converting all the bases 
into sulphates, in the manner described for converting 
potassa into sulphate (§ 44), and weighing the mixture 
of the salts ; then subtract from this the sum of tlie 
weights of calcic and magnesic sulpliate, as estimated from 
the determination of those bases, already made, and the 
remainder will be the sodic (and potassic) sulphate. 

d. To determine approximately the amount of potassa, 
if any is present, dissolve this residue of mixed sulphates 



240 § 122. FERTILIZEKS. 

in very dilute hydrochloric acid, determine sulphuric acid 
in the solution by precipitation with baric chloride (§ 59), 
deduct so much of the sulphuric acid as is estimated to 
have been combined with the lime and magnesia, and de- 
duct also the corresponding quantity of sulj^hates from 
the total amount of sulphates, and with these remainders 
estimate the potassa and soda by the formula for the in- 
direct determination of these bases (§ 4G, e). 

e. Mine licid. — This may be^ determined by SchliJss- 
ing's process in 10-20 c.c. of the aqueous solution ob- 
tained in 5, or by fusion of about 2 grms. of the salt with 
silicic acid (§ 62). This estimation an be dispensed 
with, since the weight of the nitrates equals the diiference 
between the total amount of salt taken, and the sum of 
the sulphates and chlorides, as already determined. 

/. If the Chih saltpetre is adulterated with salt, its so- 
lution will give an abundant precipitate w^ith argentic 
nitrate ; if adulterated with soda (sodic carbonate) it will 
crive the reaction for carbonic acid ; if with magnesic sul- 
phate (Epsom salts), it wall give a decided reaction for 
sulphuric acid and for magnesia ; and if with sodic sul- 
phate (Glauber's salt), it will give a decided reaction for 
sulphuric acid, but none for magnesia. 



§ 123. ASHES OF PLANTS. 241 

CHAPTER VII. 

ANALYSIS OF ASHES. 

I. 

ASHES OF PLANTS. 

123. To prepare the j^lant for incineration, it must first 
be most carefully cleaned ; and too much care cannot be 
taken in this respect, for if any particles of sand or clay 
are left adhering to the object, the accuracy of the analy- 
sis is of course thereby greatly impaired, or the analysis 
itself is rendered much more difficult of execution. 

a. Moots and tubers must be cleaned with a soft brush, 
under a current of water, and be afterwards repeatedly 
rinsed ofi" with distilled water, and immediately dried 
with a soft cloth. The dust is removed from stems and 
leaves^ when possible, by wiping them with a soft cloth. 
Seeds, particularly the larger kinds, may be put in dis- 
tilled water for a few minutes, and immediately, before 
the water can have time to penetrate them, put on a 
sieve to drain, laid on filter paper and dried as quickly 
as possible between soft cloths. 

b. To dry the green ^9«r^s of plants and fleshy roots, 
hang them on threads in a drying-chamber, the roots 
being cut in thin slices. Tubers may be dried in the same 
way. Roots and tubers so dried are then coarsely pul- 
verized in the mortar, while leaves and stems are cut up 
with clean shears ; seeds are broken up to a coarse powder 
in a mortar. 

c. The incineration is best effected in shallow platinum 
trays, that are heated over the gas-lamp, or in large cast- 
iron muffles, about 50 cm. long and 13 cni. wide^ built 

11 



242 § 123. ANALYSIS OP ASHES. 

into an appropriate furnace in such a manner as to be 
heated mostly at the sides and on the top. The heat 
must, at first, ba kept very low for several hours, or even 
days, while the substance is slowly charred ; the coal, 
•when so slowly formed, takes a more porous consistency. 
"When the evolution of gases has nearly ceased, the heat 
may be gradually raised, but not at any time to a percep- 
tible red ; in this way, at least in the incineration of most 
of the fodder-plants, roots, and woods, that yield an ash 
rich in carbonates, a perfect combustion is obtained with- 
out fusing the ash. In case some coal remains, that re- 
sists combustion without applying too high a heat, exhaust 
it with hot water two or three times ; the washed residue 
is usually very easily burned. Then either add the aque- 
ous solution just obtained to the ash, evaporate the mix- 
ture to dryness on the water-bath, ignite the residue very 
gently, and weigh it ; or weigh the last ash, and bring 
the aqueous extract of the coal to a certain volume, and 
for each part of the subsequent analysis, mix together 
equal fractional parts of ash and extract. 

Substances rich in silica, as the grasses, and the stems 
and chaff of cereals, and also seeds rich in alkaline phos- 
phates, are with difficulty made to yield an ash that is free 
from coal. Such substances should first be charred at a 
very low temperature ; then, without disturbing the coal 
in the dish, moisten it with a cold saturated solution of 
baric hydrate, dry the moistened mass, and ignite it in the 
mufile at a barely visible red heat ; the completion of the 
incineration generally requires from 8 to 12 hours. Enough 
baryta water must be added, by moistening and drying 
the coal several times, so that the ash will contain about 
half its weight of baryta. The addition of this substance 
almost entirely prevents the escape of the chlorine, effects 
a more speedy combustion of the coal, makes the silicates 
decomposable by acids, and insures the presence of phos- 
phoric acid in the ash in a readily determinable form. 



§ 124. ASH RICH IN- CARBONATES, POOR IX SILICA. 243 

The whole quantity of the ash, in whatever way ob- 
tained, should be most carefully pulverized and mixed 
together before any sam2)le is taken for analysis. 



A. ASH RICH IN CARBONATES, AND POOR IN SILICA. 

124. a. Carbonic acid. — Determine this in 1-2 grms., 
using nitric acid to expel the carbonic acid. 

h. Chlorine. — Estimate this in the nitric-acid solution 
obtained in 6f, after filtering out the insoluble portion. 

c. Silica, sand, and coal. — Moisten a portion (3-4 grms.) 
in a flask, with concentrated nitric acid, add concentrated 
hydrochloric acid, and* digest the mixture for a long time 
at an almost boiling heat. Rinse the whole into an evapo- 
rating dish, evaporate to dryness, moisten the residue with 
hydrochloric acid, and proceed to eliminate and deter- 
mine silica, sand, and coal, as directed in § 58, a, 3. 

If the ash contains no sandy particles, as may be shown 
by the absence of any grittiness when the residue, insolu- 
ble in hydrochloric acid, is stirred with the glass rod, the 
boiling with sodic carbonate may be omitted, and nothing 
need be done but collect the silica on a weighed filter, dry 
it at 110°, weigh it, and ignite, and weigh it again, to 
determine the unconsumed carbon that may be mixed 
with it. 

If there are more than a few centigrammes of this carbon 
in three or four grammes of the ash, the substance has not 
been properly incinerated, and very unreliable results 
may be obtained in the analysis, particularly as regards 
the phosphates and the alkalies. 

d. Complete analysis. — Bring the filtrate from the in- 
soluble portion to a volume of 500 c.c, and examine it 
according to Scheme IV., § 94. If more than traces of 
manganic oxide are present, and it is desired to estimate 
this base, proceed according to Scheme III., § 94, 



244 § 124. ANALYSIS OF ASHES. 



B. ASH RICH IN SILICA, MIXED WITH BARYTA. 

a. Determine carbonic acid and chlorine, and pre- 
pare the solution for the complete analysis, precisely as 
under A. 

The residue, insoluble in hydrochloric acid, on eliminat- 
ing silica in the usual way, contains, besides sand and 
unconsuraed carbon, baric sulphate, in which is the sul- 
phuric acid of the ash, and it must be treated accord- 
ingly. Collect it on a dried and weighed filter, wash it, 
dry it at 110° C, and weigh. Then treat it with sodic 
carbonate (§ 58, a, 2) ; but, as the baric sulphate is not 
readily decomposed by the carbonated alkali, the boiling 
must be repeated several times, with fresh portions of the 
carbonate, the insoluble part allowed to settle completely 
after each boiling, and the clear liquid decanted without 
transferring any notable quantity of the solid to the filter ; 
when the filtered liquid gives no reaction for sulphuric 
acid, after acidification with hydrochloric acid, the decom- 
position may be considered as ended ; if the portion with 
which the test is made gives a reaction with baric chlo- 
ride, it should be put back kito the liquid to be boiled. 

Transfer the silica and coal to the filter, after the boil- 
ing is finished, pour dilute hydrochloric acid over it as 
long as there is any efi*ervescence, wash the filter care- 
fully with water, dry at 110°, weigh, ignite, and weigh 
again, and so estimate sand and unconsumed carbon, as 
under A. 

Evaporate the alkaline solutions and washings to dry- 
ness, and eliminate silica (§ 58), and determine sulphuric 
acid in the filtrate from the silica, with the aid of baric 
chloride (§ 59). 

t.-^. -Complete analysis. — Examine the solution obtained 
in a, and filtered from the silica, etc., according to Scheme 



§ 124. MISCELLANEOUS DETERMINATIONS. 245 

III. or IV., § 94, Avitli these exceptions, that sulphuric acid 
need not be determined under a, and that, before precipi- 
tating lime by ammonic oxalate, the barium should be 
removed by precipitation with a very dilute sulphuric 
acid, containing but one part of acid in 300-400 of water ; 
the precipitated baric sulphate should be examined for 
lime by heating the moist precipitate with ammonic car- 
bonate, washing it, and then treating it with dilute hydro- 
chloric acid, neutralizing the acid with ammonia, and 
adding ammonic oxalate. 

C. MISCELLANEOUS DETERMINATIONS. 

a. Sulphur. — A part of this is volatilized during the 
process of incineration. In order, therefore, to determine 
the total amount in the plant, treat 4-5 grms. of the dry 
substance with fused potassic hydrate and nitrate (§ 92). 

b. Sulphuric acid, already formed in the plant,— A 

few cultivated plants contain more than mere traces of 
this acid. To determine it, and also the chlorine, if it is 
desired, prepare an extract of the jDlant by water contain- 
ing ^1,0 of nitric acid. 

Draw out one end of a glass tube, about 60 cm. long 
and 1-1^ 1 2 cm. in diameter, in such a manner that a rubber 
tube and clamp can be attached, after the fashion of a 
Mohr's burette. Close the throat of the tube, where it 
begins to taper into the smaller tube, with a plug of cot- 
ton that has been previously boiled in the acidulated 
water, such as is to be used for the extraction. Put 8-10 
grms. of the dried substance in the tube, fill the latter 
with the acidified water, and let the two remain in contact 
several hours ; then open the clamp, let some of the water 
run off, add fresh acidified water, and repeat the operation 
until the extract gives at the most the merest opalescence 
with argentic nitrate. 



246 § 125. ANALYSIS OF ASHES. 

In this acid solution precipitate sulphuric acid with baric 
acetate, and chlorine with argentic nitrate in the filtrate 
from the baric sulphate ; treat this last j^recipitate as one 
produced in the presence of organic matter, if it is at all 
abundant. 

125» The following method of incineration and analysis 
is given by Reichhardt, by which the volatilization of any 
mineral matters is avoided, as well as the addition of any- 
thing to the ash to facilitate incineration. 

1. Carefully char enough of the dried substance to yield 
2 grms. of ash, pulverize the coal, and exhaust it with 
several portions of hot water. 

a. Add argentic nitrate to this extract immediately. 

b. Exhaust the coal with water containing a little nitric 
acid, wash with the same, and add this extract to a. 

2. Incinerate the coal completely, and exhaust the ash, 
first with water, and then with moderately concentrated 
nitric acid, and add these extracts to those obtained in 1. 

3. Determination of sulphur and chlorine. — The pre- 
cipitate by argentic nitrate, in these extracts, contains the 
suljDhur that was present in a soluble form in the plant, 
and the chlorine. Acidify the mixture of precipitate and 
liquid with nitric acid, if not already acid, collect the 
precipitate of argentic sulphide and chloride on a dried and 
weighed filter, wash it well, and add the filtrate and wash- 
ings to those obtained in 4, below. 

Treat the precipitate on the filter with ammonia, by 
TV hich the argentic chloride is dissolved, wash the insolu- 
ble argentic sulphide, dry it at 100°, and weigh. It con- 
tains 12.9"! „ of sulphur. 

Precipitate argentic chloride in the amnionic extract, by 
nitric acid in excess, and treat the precipitate in the usual 
manner (§ 63). 

4. Heat the residue, insoluble in nitric acid in 2, with 



§ 126. MISCELLANEOUS DETERMINATIONS. 247 

concentrated hydrochloric acid, and filter. By mixing this 
filtrate with that obtained in 3, the excess of silver is pre- 
cipitated, and may be removed from the solution by fil- 
tration. 

5. Treat the residue, insoluble in hydrochloric acid, as 
directed in § 58, «, 3, for the separation of silica, sand, 
and coal. 

6, Eliminate the silica in the hydrochloric solution fil- 
tered from the excess of silver in 4, in the usual manner 
(§ 58, a., 1), and examine the filtrate from the silica ac- 
cording to Scheme III. or IV., § 94, according to whether 
manganese is or is not to be determined. 

126. Statement of results. — So much sodium as is nec- 
essary to combine with all the chlorine should be consid- 
ered as so combined, while the remainder of the sodium is 
given as sodic oxide. 

If there is not sodium enough for this purpose, take 
enough of the potassium to combine with what chlorine 
is left, and give the remainder of the potassium as potassic 
oxide. 

The manganese is to be given as manganous manganic 
oxide, Mn30^. 

The sand and coal are accidental ingredients of the ash, 
and therefore the percentage composition should be calcu- 
lated with reference to what is left after subtracting these 
from the weight of ash taken for analysis. 

The percentage composition should moreover be given 
with reference to the remainder left after subtracting the 
carbonic acid also, since this is not properly one of the 
mineral substances found in the plant, but results from the 
combustion of the organic acids. 

The first statement enables one to judge of the accuracy 
of the analysis, and the second gives the real composition 
of the mineral matter found in the particular plant exam- 
ined. 



248 



127. AiNALYSIS OF ASHES. 



Analysis of the ash of hops. (Wheeler.) 



Potassa , 

Soda 

Lime 

Magnesia 

Ferric oxide 

Manganous mauganic oxid 

Alumina , 

Phosphoric acid 

Snlpburic acid 

Potassic chloride , 

Sodic chloride , 

Silicic acid 

Carbonic acid 

Charcoal aud saud 

Total ash 



CO2, coal, 




etc., 


CO2, etc., 


included. 


deducted. 


37.79 


44.33 


11.36 


13.33 


1.27 


1.49 


0.48 


0.56 


trace. 




trace. 




12.67 


14.86 


1.98 


2.32 


8.48 


9.94 


1.21 


1.41 


10.02 


11.76 


12.50 




1.91 




99.07 


100.00 


9.14 





II. 



THE ASH OF ANIMAL SUBSTANCES. 



127. Animal substances are incinerated with difficulty, 
particularly when they fuse before they become charred ; 
the attempt should be made, however, to burn them with- 
out the addition of any agents. 

First char the dry substance in a platinum dish, raising 
the heat very slowly, so as to avoid fusion, if possible ; 
when the charring has attained such a point that water is 
no longer colored wlien left for a time in contact with the 
coal, break the coal up into a coarse powder, and boil and 
wash it several times witli water, acidified with a little 
nitric acid in case no carbonates are present, or carbonic 
acid is not to be determined ; then dry the coaly residue 
and complete the incineration in the muffle, at a barely 
visible red heat. 

Sometimes it wdll be found necessary to repeat the 
exhaustion with water and heating in tlie muffle several 
times, before the incineration can be completed. 



§ 128. ASHES OF FUEL. 249 

This process, ^vill, however, hardly succeed in many 
cases, and usually only when the ash yielded by the sub- 
stance is rich in alkaline carbonates or sodic chloride, or 
when but a small quantity of the substance is incinerated 
in order to determine the total amount of ash. Since a 
considerable proportion of alkaline phosphates is often 
l^resent, which is converted into pyrophosphate during 
the incineration, it is generally necessary to treat the 
charred substance with baryta water, in the manner di- 
rected for the incineration of vegetable substances rich in 
phosphates. 

In the analysis of the ash, proceed as directed for the 
analysis of ashes of plants, with the exception that, since 
silicic acid and sand are rarely present, the Avork is some- 
what simplified. The total sulphur should be determined 
in a portion of the substance that has been heated with 
potassic hydrate and nitrate (§ 92). 

III. 

ASHES OF rUEL. 

128. a. Carbonic Acid, — Determine this in 2 grms. 
h. Chlorine. — Determine this in the nitric-acid solution 
obtained in a. 

c. Complete Analysis. — Conduct this as directed for the 
analysis of the ash of plants poor in silica. (§ 124, e, d.) 
The estimation of potassa and phosj^horic acid is of most 
importance in respect to the agricultural value of the 
ashes. 10-15 grms. of wood ashes, or 15-25 grms. of 
peat or coal ashes, should be treated with acid, in order to 
j^repare a sufficient quantity of the solution. 

d. Potassa. — For a volumetric determination of potassa 
that will answer very well for practical purposes, treat 
6.91 grms. of the wood ashes in a flask of about 300 c.c. 
capacity with 5-6 grms. of caustic lime and 40-60 c.c. of 

11* 



250 § 128. ANALYSIS OF ASHESt 

water, and heat the mixture to boiling. Filter the solu- 
tion into a graduated cylinder, and wash the insoluble 
residue with sufficient Avater to make the volume of the 
solution exactly 100 c.c, when properly cooled. Titrate 
10 c.c. of this solution with the normal acid (§ 44,/*), 
subtract 0.3 c.c. for the excess of lime, and then multiply 
the number of cubic centimetres required by 10, for the 
per cent of potassic carbonate. 

Peat and Coal Ashes are usually very poor in alkalies 
and phosphoric acid. Their agricultural value depends 
more particularly on the amount of calcic sulphate 
(gypsum), and calcic carbonate and phosphate, which they 
contain. 

Many kinds of peat leave ashes that are rich in gypsum ; 
in such cases it is well to boil about 2 grms. of the ashes 
an hour, with a solution of 6-8 grms. of sodic carbonate, 
and determine sulphuric acid in the aqueous solution so 
obtained, and lime in the hydrochloric solution of the 
residue insoluble in water. 



§ 129. FODDER. 251 

CHAPTER VIII. 

FODDER AND FOOD. 

I. 

FODDER. 

129. In the examination of fodder, it is very desirable 
that chemists should follow a common method. 

The processes of analysis that have been perfected at 
the experimental station, Weende, by Henneberg, Stoh- 
mann, Rautenberg, Kiihn, Aronstein, and Schulze, com- 
mend themselves for general use. 

a. Preparation of the Sample for Analysis.— In order 
that the sample may fairly represent a large quantity of 
the foddei', a handful should be taken here and there from 
all parts of the pile or the field, till 15-20 such portions 
are obtained: mix the whole well together, and take 
about 1 kilo, of dry fodder or 3-4 kilos, of green for the 
sample. 

Cut it up with shears, weigh it, dry it for several days 
in a drying-chamber at 50-00°, expose it to the air 24 
hours, and weigh it again in this air-dried condition. 

l. Hygroscopic Water. — Grind 50 to 100 grms. of the 
dry substance quickly in a steel mill and desiccate 10 grms. 
of this powder at 110° C. 

c. IVon-VOlatile Matter. — Incinerate the dried sub- 
stance obtained in 5, subtract carbonic acid and coal, and 
calculate the non-volatile matter in the fodder as it was 
taken for analysis. 

130. Reduce the rest of the air-dried substance to a 
fine powder, by alternate grinding and sifting, and pre- 
serve it in well-stopjDcred bottles. 

a. Water. — Desiccate 3-5 grms. of this powder at 



252 § 130. FODDER AND FOOD. 

110° C, and calculate the amount of dry substance in the 
powder. 
h. Protein Compounds.— Ignite 0.7 to 1 grm. with 

soda-lime (§ 85). 

c. Fatty Substances.— Extract these from 6-8 grms., 
by ether (§ 87). 

d. Crude Cellulose.— Boil a quantity of the powder 
containing about 3 grms. of dry substance, half an hour, 
with 200 c.c. of dilute sulphuric acid, containing 1.25° !„ 
of monohydrated acid, in a flask that is attached to the 
lower end of a Liebig's condenser ; let the mixture stand 
till the solid particles settle to the bottom ; draw the clear 
liquid off into a beaker, as completely as possible, with a 
small siphon, and finally Avith a pipette ; pour 200 c.c. 
of water over the residue in the flask, boil again half an 
hour in the same manner as before, and as before let the 
solid particles settle and remove the clear liquid ; repeat 
this operation once more. 

Then boil the substance in the same way with 150 c.c. 
of water and 50 c.c. of a solution containing 50 grms. of 
fused caustic potash in the litre, and afterwards twice with 
200 c.c. of water, removing the liquid each time in the 
same manner as described for the sulphuric acid, but put- 
ting these alkaline washings in a beaker by themselves ; 
finally, bring the residue on a dried and weighed filter. 
Then, with the siphon, draw off the clear alJcaline liquid 
from any sediment that may have been deposited in it ; 
transfer this sediment to the same filter, and wash the 
whole, as long as the washings have an alkaline reaction ; 
then add the sediment in the beaker containing the acid 
washings, after drawing off the clear liquid with the 
siphon, and wash again, as long as the washings have an 
acid reaction. Wash the contents of the filter succes- 
sively with alcohol and ether; dry the filter and its con- 
tents at 110°, weigh, incinerate the residue, and weigh 



§ 131. FODDER. 253 

the ash. The difference between the total weight of the 
insoluble residue and that of the ash equals the crude 
celhilose or fibre. 

The residue obtained in this way is a mixture of cellu- 
lose witli various other substances. When obtained from 
the grasses it is comparatively the purest, but contains 
2-3" I Q of protein compounds. When prepared from clover, 
it contains 5-6" \^ of the same substances ; but even after 
subtraction of these albuminoids, the residue contains 
1-T"lg more carbon than pure celhilose. 

131, a. Dry Matter Soluble in Water. — To determine 
the amount of substance soluble in water, boil 10-20 
grms. with 10-12 successive portions of 200-300 c.c. of 
water in a flask that is connected with the lower end of a 
Liebig's condenser (§ 39, <:•), and after each boiling, sepa- 
rate the water as quickly as possible from the residue ; all 
the portions of water are afterwards passed through a 
ribbed filter, that is pierced w^ith the glass rod and 
replaced by a new one as often as it becomes choked up, 
so that the filtration shall proceed as rapidly as possible. 
Bunsen's method of filtration can be iTsed in this case to 
great advantage. 

The extraction should, at any rate, be finished in one 
day, so that the solution may not begin to mould before 
it is examined. 

Evaporate 200 c.c. of the extract almost to dryness, in 
a platinum dish, on the water-bath ; complete tlie desic- 
cation on hot sand, under the receiver of the air-pump 
(§ 90), and weigh the residue. 

b. Non-volatile Matter Soluble in Water. — Incinerate 
the residue obtained in a. Generally an ash free from 
coal can be obtained ; if not, filter out and weigh the 
coal in the usual manner, and subtract it and the carbonic 
acid from the total residue. 

An excess of mineral matters is always found in this 



254 § 131. FODDER AND FOOD. 

solution, for the water dissolves some of the glass with 
which it comes in contact. 

If it is not desired to subject the residue insoluble in 
■water to further treatment with alcohol and ether, as 
below, it can be dried and weighed, and ash and nitrogen 
determinations made with portions of it ; then, by sub- 
tracting the amount of ash and nitrogen found in it from 
what Avas found in the original substance, the amount that 
should be found in the aqueous extract may be estimated, 
and thus the tedious evaporation of a portion of that 
extract to dryness be avoided ; or the two sets of deter- 
minations may be made to control each other ; the differ- 
ence between the amount of substance taken for extraction 
with water and the weight of the insoluble substance, 
above determined, will give the amount soluble in water. 

Or, since the alcohol and ether used for extracting the 
residue insoluble in water, as below, usually take up but 
traces of mineral matters, we can, in case these solvents 
take but a few per cent of that residue into solution, 
consider the residue insoluble in alcohol and ether as con- 
taining the same amount of ash ingredients as the residue 
insoluble in water only, and the determination of the 
ash in this will answer the same purpose as if estimated 
in the first insoluble residue. 

c. Nitrogen in Forms Soluble in Water. — Evaporate 
500-1000 c.c. of the aqueous extract to a syrup, on the 
water-bath, absorb the residue by as small a quantity of 
calcined gypsum as possible, collect the whole in a watch- 
glass, dry it for a while at 88-90° C, and ignite the residue 
with soda-lime (§ 85, a). 

d. Actual Ammonia. — Determine this in a portion of 
the aqueous extract, by Schlossing's method. Acidify 
300 c.c. of the extract with hydrochloric acid, and con- 
centrate it. A more accurate result may be obtained by 
Knop's method of setting free the nitrogen and measuring 



§ 131. FODDEK. 255 

its volumie in the azotometer. {See Fresenius's Quan- 
titative Analysis.) 

e. Suj^ar and Gum in Aqueous Extract, — Evaporate 
500 to 1000 c.c. nearly to dryness, as quickly as it can be 
done without loss, and, if possible, in a space where the 
air can be rarefied, and exhaust the moist residue with 
alcohol of 80-85" |g, by repeated boihng with fresh j^or- 
tions of the solvent, as long as it is colored. Filter the 
liquid, add water to the filtrate, expel the alcohol by heat, 
filter through animal charcoal, if necessary, bring this 
filtrate to a certain volume, and estimate glucose and 
saccharose (§ 81). 

Dry the residue insoluble in alcohol at 100° C, weigh, 
and incinerate it. Subtract the ash and protein com- 
pounds, as may be estimated from determinations already 
made, from the total amount of the residue insoluble in 
alcohol, and call the remainder ginn and vegetable acids. 

f. Nitric Acid. — To control the determination of nitro- 
gen already made in a portion of the aqueous extract, 
nitric acid may be determined, in addition to the ammonia 
already estimated; thus it may be learned how much 
of the nitrogen is present in the form of these inorganic 
substances. 

Evaporate 500-1000 c.c. of the aqueous extract to a 
small bulk, and determine nitric acid by Schlossing's 
method (§ 62, a). 

Friihling and Grouven {LandwirthscJi. Yersuchs-Sta- 
tionen, 9, 9) prepare the aqueous extract of the plant, 
particularly for the determination of nitric acid, as fol- 
lows : Put 100-500 grms. of the finely divided but not 
ground air-dried substance in strong beakers of a capacity 
of two litres; add enough 50" j^ alcohol, so that the whole 
mass of the solid will be completely covered, when pressed 
down firmly with a pestle and kept down by a plate 
•weighted with a glass filled with mercury. 



256 § 132. FODDER AND FOOD. 

After 12 hours, pour off the dark-colored liquid, wrap 
tlie solid mass in a Hnen bag, and, Avith a powerful screw- 
press, force out the i-emainder of the alcohol. Pour 
diluted alcohol over the press-cake 4 or 5 times, and each 
time j^ress the liquid out completely. In this way 1-2 
litres of a highly-colored alcoholic extract are obtained. 
Heat the liquid almost to boiling till all the alcohol is 
volatilized, evaporate it to a small bulk, add an excess of 
rather thick milk of lime, and boil the mixture for some 
time ; allow the precipitate to subside, draw off the clear 
liquid with a siphon, filter the remainder through linen, 
and wash the residue well ; heat the solution thus ob- 
tained, pass carbonic acid through it, boil and filter; 
evaporate the filtrate to a small bulk, and use the whole 
of it for the determination of nitric acid by Schlossing's 
process (§ 62, a), in case there is reason to believe that but 
little is present ; or a i)art of it may be used for this pur- 
pose, and the remainder treated as directed above for the 
examination of the aqueous extract. 

132. If it is desired to estimate still more in detail the 
non-nitrogenou8 substances in the fodder, boil the residue 
that is insoluble in water (§ 131, a), first with common, 
and then with absolute alcohol, so long as the washings 
are colored; then extract this second residue with ether; 
these extractions can be most conveniently made with the 
aid of the washing-bottle filtering arrangement (§ 39, c). 

a. Evaporate both the extracts, or aliquot parts of 
them, to dryness, to determine the amounts taken into 
solution. 

h. Crude Cellulose. — Treat 2-4 grms. of the residue 
that has been exhausted with alcohol and ether above, as 
directed in § 78. 

In case solid excrements are being analyzed to deter- 
mine the amount of cellulose in them as compared with 
fodder, a longer maceration is advisable, for 14-16 days, 
instead of 12-14. 



§ 133. 



BEETS, TURNIPS. 



257 



c. starch. — Wash 2 grms. of the 230wdered substance 
on a filter, with cold water, and then, if much ghiten is 
present, wash with alcohol containing sulphuric acid, and 
finally with water. Treat the residue with dilute sul- 
phuric acid or malt, to convert the starch into glucose, 
and estimate the glucose with the standard cupric solution 

(§ 81). 

The difiTerence between the sum of the weights of the 
cellulose, protein compounds, and mineral ingredients in 
the dried substance, and the Aveight of the substance 
insoluble in water, alcohol, and ether, gives the amount of 
difficultly soluble non-nitroge7ious matters, of which starch 
will form a considerable part. 

Analysis of the Pea. (Voelcker.) 



"Water 

Ash or Don-volatile matter. . . 

Protein compounds 

Fat 

Cellulose (fibre) 

Starch 

Su^ar 

Other uou-nitrogeuous matter 



Pea. 


Pod. 


Yme. 


14.1 


13.68 


16.03 


2.5 


2.75 


4.93 


23.4 


7.13 


8.86 


3.0 


1.09 


2.34 


10.0 


53.71 


43.79 


37.0 






2.0 






9. 


31.65 


25.06 


100.00 


100.00 


100.00 



BEETS, TURNIPS. 



133. To estimate the value of tliese for fodder, deter- 
minations of water, albuminoids, mineral matters, cellu- 
lose, and the total amount of other non-nitrogenous 
matters, are important. 

For the manufacture of sugar, the estimation of this 
ingredient is of greatest importance. 

The part of the beet that is insoluble in water consists 
mostly of cellulose and pectose, while in the aqueous solu- 
tion, sugar, inorganic salts, and albuminoids, are to be 
found. 

a. Water. — Slice the roots after they have been proper- 



258 § 133. FODDER AND FOOD. 

ly cleaned ; or, if they are very largo, select 15-20 from 
the lot, cut each one in halves from top to bottom, and 
take a thin slice from the inside of each half. 

If sugar is to be determined for technical purposes, the 
crown and end of the root should be cut off, in the man- 
ner practised at the manufactory, before slicing it. 

Weigh quickly the whole number of slices thus ob- 
tained, to the amount of 500-1000 grms., and dry them 
on threads in the drying-chamber at a temperature of 
60-70° C. Pulverize this dried substance coarsely, mix it 
well together, and weigh the whole quantity, determine 
hygroscopic loater in a portion of 5-6 grms., and keep the 
rest in well-stoppered bottles. 

h. Non- volatile matter, nitro^^en, fat, crude cellulose. 

— ^Determine these as directed under Fodder (§ 1129, c, 
§ 130, h, c, d). 

c. Pectose compounds. — These are estimated by the 
difference between the weight of the dry substance and 
the sum of the Aveights of the above-named substances in 
Zi>, and the sugar. 

d. Sugar, — Boil 2-3 grms. of the powdered substance 
with several fresh j^ortions of 80-85° 1^ alcohol, as long as 
anything appears to be taken into solution ; j^our each 
portion of alcohol through a filter that has been dried at 
100° and weighed, and finally put the whole insoluble 
substance on the same filter, wash it with hot alcohol, dry 
it at 100°, and weigh, ignite it, and weigh the ash. The 
amount of organic matter, burned off by the ignition, 
can then be estimated ; it consists almost entirely of sugar. 

To determine the sugar more accurately, add considera- 
ble water to the alcoholic solution, heat the mixture on 
the water-bath until the alcohol is entirely evaporated, di- 
lute the residue to about 300 c.c, add 5-6 c.c. of concen- 
trated sulphuric acid, heat the mixture 3 hours on the 
water-bath, neutralize the free acid with sodic carbonate, 



§ 133. BEETS, TURNIPS. 259 

and determine glucose in an aliquot part of the solution, 
having first added water, if necessary, to make the volume 
of the solution one that can be easily divided into aliquot 
parts ; calculate the result obtained for saccharose, if the 
root examined was the sugar beet ; in other roots, and in 
the sap of plants, glucose is found, as well as cane sugar, 
and the determination should be made accordingly (§ 83). 

To examine the root in its fresh state for sugar, enclose 
a weighed quantity of the finely grated root in a flannel 
bag, and press the sap out of it ; weigh the press-cake, 
and determine water in one portion of 20-30 grms. by 
desiccation at 100° ; on the basis of this determination, 
the amount of sugar still remaining in the cake can be 
estimated, the solution in the cake being of course of the 
same strength as that expressed. 

Weigh or measure the sap that was pressed out, and 
determine sugar in an aliquot part of it. 

In the ease of the sugar beet, it may be assumed with 
tolerable safety that it contains 94° |g of water, and Ave 
may therefore express a small quantity of the sap from a 
weighed quantity of the grated root, and determine sugar 
in 50 c.c. of it, in the usual manner (§ 83). 

An approximate estimation of sugar in beets may be 
made by determining tlieir specific gravity according to 
the method described in § 35, e. 

Take 10-12 beets from difierent parts of the lot, clean 
them carefully, cut each one in four equal sections, across 
its longitudinal axis, and use the second piece from the 
top for the determination of the specific gravity. The 
temperature of the saline solution should be about 18° C. 

The relation between the specific gravity of the beet 
and the percentage of sugar, as well as of total dry sub- 
stance, is given in Table VI. 

When, in these estimations of sugar with the cupric so- 
lution, the solution of sugar is not properly clarified by 
the plumbic acetate, heat a measured quantity of it nearly 



260 § 133. FODDER AND FOOD. 

to boiling, add a few drops of milk of lime, whereby a 
heavy precipitate is usually produced ; then filter the 
liquid through granular animal charcoal, free from dust, 
and repeat this filtration until the solution is sufi&ciently 
decolorized. If any evaporation of the water is avoided 
in the course of this operation, the sugar can be deter- 
mined at once in a measured portion of the filtrate ; other- 
wise, the coal must be well washed, the filtrate and wash- 
ings perfectly mixed, and the estimation of the sugar, for 
the whole amount of solution taken originally, based upon 
the ratio between the volume of this solution and that in 
an aliquot part of which the sugar is determined with the 
cupric solution. 

€. Ammonia. — Treat 30 c.c. of the sap with enough 
plumbic acetate to effect complete precipitation, filter the 
liquid, and use 20 c.c. of the filtrate for the determination 
by Schlussing's process {§ 47, b). 

f, Nitric acid. — Determine this according to Schloss- 
ing's process (§ 62, «), in 10-20 c.c. of the concentrated 
sap, containing not more than 2-2.5 grms. of organic mat- 
ter ; an amount of ferrous chloride, containing 6-7 grms. 
of metallic iron, should be used for 1 grm. of dry sub- 
stance in the quantity of sap taken. 

Huojo and Ernst Schulze found it best to make an alco- 
holic extract of from 4-10 grms. of the dried and powder- 
ed root, according to its richness in nitric acid, with 90° \^ 
alcohol, with the aid of heat ; the extract was evaporated 
to dryness, the residue dissolved in water, and the solu- 
tion filtered, if necessary ; nitric acid was determined in 
this filtrate. {Landtoirthsch. T^ersuchs-Stationen, 9, 447.) 

g. Starch* — Some roots, and particularly carrots, con- 
tain a notable quantity of starch. To estimate it, mash 
an amount of the root containing 3-4 grms. of dry sub- 
stance with cold water, rinse the mixture into a beaker, 
add more water, stir the whole, and let it stand half an 



§ 134. POTATOES. 261 

hour ; decant the supernatant liquid on .1 dried and 
weighed filter, and finally transfer the insoluble residue to 
the same filter ; wash the filter well with cold water, re- 
move most of the water from its contents by pressure 
between folds of filter-paper, dry the whole at 100°, and 
weigh. Treat the filter and its contents with extract of 
malt, and determine glucose in the product (§ 81). 

POTATOES. 

134. Prepare them for examination as directed in § 138, a. 

a. Water. — Dry 250-500 grms. of the potatoes, and 
determine hygroscopic water also, as directed in § 133, a, 
in the examination of roots. 

J). Dry substance soluble in water. — Cut several pota- 
toes very fine, and crush 30 grms. )f the carefully mixed 
sample with cold Avater, in a mortar, and separate the 
soluble from the insoluble part in the same manner as di- 
rected in § 133, g. 

Dry the insoluble residue at 100" C, weigh it, inciner- 
ate it in the mufile (§ 123, c), and weigh the ash ; thus we 
have determined the organic and the inorganic matter in- 
soluble in water. The difference between the weight of 
the dried insoluble residue and the amount of substance 
taken gives the weight of soluble matter in it. 

Bring the aqueous solution to any easily divisible vol- 
ume, and heat about ^ I3 of it to hoiling. Albumen is pre- 
cipitated, and may be collected on a weighed filter, dried 
at 100°, and weighed. 

Evaporate the filtrate from the albumen to dryness on 
the water-bath, weigh the residue, ignite it, and weigh the 
ash ; thus organic and inorganic matters, soluble in 
water, are determined. 

c. Albuminoids. — Evaporate another third of the solu- 
tion almost to dryness, mix the moist residue with calcined 



282 g 135. FODDER AND FOOD. 

gypsum, dry it at 100-105° C, and ignite the residue 
with soda-lime (§ 85). 

d. Starch. — Determine this, together with a small quan- 
tity of gum, in 2.5-4 grms. of dry substance (§ 79). 

For technical purposes, it is often sufficient to determine 
the si^ecific gravity of the potato, in order to estimate ap- 
j^roximately the goodness of the tuber, or the amount of 
dry substance and starch that it contains. 

Determine the specific gravity as directed in § 35, e. 
The temperature of the saline solution should be about 
1G° C. The relation between the specific gravity and the 
amount of dry substance and starch is given in Table YII. 
Potatoes that have been affected by disease cannot be 
examined in this way unless the diseased parts are cut out. 

Artichokes may be examined in the same way as 
potatoes, excejDt that the aqueous extract of the former 
should be more carefully examined for glucose. Tlie 
inuliu in the artichoke is converted into glucose somewhat 
more easily than the starch in potatoes. 

SEEDS. MEAL. ELOUR. 

1S5. Seeds are crushed in a mortar or ground to a fine 
powder in the steel mill. 

«. Water. — Desiccate 5-10 grms. of the powder, and 
preserve the rest in well-stoppered bottles. 

h. Non-volatile matter, protein compounds, fat, crude 
cellulose. — Estimate these precisely as directed for the 
examination of fodder (§ 129, c, § 130, 5, <?, dj). 

c. Dry substance soluble in water. — Determine this 
as directed in § 134, 5, with 20 grms. of the powder. 

d. Starch. — Follow any of the methods described in 
§79. 

Or, wash 2 grms. of the powder on a filter, first with 
cold water, then with alcohol containing sulphuric acid. 



§ 136. MILK. 263 

to take out the gluten, and again with water ; then pierce 
the filter with the glass rod, wash its contents into a flask, 
tear the filter into shreds, and boil it hy itself with water 
cqntaining 4 or 5 droj^s of 20° 1^ suljjlmric acid, and finally 
add it to the contents of the flask; the total amount of 
solution thus obtained should not be over 100 c.c. ; pro- 
ceed as usual with the conversion of the starch into glu- 
cose (§ 79). 

In most seeds there is but little gnm or sugar; one can 
therefore proceed at once to treat the seeds with alcohol 
acidified with sulphuric acid, as above, remove the alcohol 
by heat, and convert the starch into glucose. 

MILK. 

136, a. Water,— Boil 50 grms. of the milk with 8 
grms. of powdered crystalline gypsum, or with 30-40 
grms. of baric sulphate (§ 90, 7i), and after the coagula- 
tion has taken place, evaporate the mixture to dryness on 
the water-bath, with constant stirring towards the end of 
the operation, and dry the residue at 100° as long as it 
loses weight. 

Or, the desiccation may be completed on hot sand in 
rarefied air (§ 90, g). 

h. Total non-volatile matter, — Evaporate 30 grms. of 
the milk to dryness, with the addition of a little acetic 
acid, and incinerate the residue in the muffle at the lowest 
possible temperature. 

c. Protein compounds. — These may be estimated by 
the remainder left after subtracting the sugar, butter, and 
ash, from the total dry substance ; this residue consists 
mostly of casein. Or, nitrogen may be estimated in the 
usual manner (§ 85) in the residue left on evaporating 6-7 
grms. of the milk to dryness with powdered gypsum or 
baric sulphate, as above. 

Albumen is contained in milk in but small proportion ; 



2G4 § 136. FODDER AND FOOD. 

in the case of some diseases, it occurs in larger quantity. 
To estimate it, coagulate 100 grms. of the milk Avith ren- 
net, at a temperature of about 45° C, filter out the pre- 
cipitate, and wash it, and heat the filtrate and washings 
to boiling. Collect the precipitated albumen on a dried 
and weighed filter, dry it at 100 C, and weigh it. 

d. Butter* — Extract the residue obtained in a with 
ether (§ 87). 

Various other and shorter processes are given for test- 
ing the goodness of milk in this respect, in one of which 
the cream is estimated by volume. 

Provide a shallow glass dish in the form of an inverted 
bell-jar, Avith a ground glass 23late to cover it and prevent 
evaporation of the milk, and a narrow orifice below, closed 
Avith a glass stopper ; a graduated cylinder holding 100 
c.c. Avill also be needed. 

Put 100 c.c. of cooled milk into the dish, and let it stand 
24 hours, at a temperature of 12-15° C. ; then loosen the 
stopper below, and let the milk flow out from underneath 
the cream into the graduated cylinder. After about ^|^ 
of the milk has run out, stoj) the flow for a few minutes, 
to allow the cream to collect together somewhat, and then 
let the milk flow out again, but only drop by drop, until 
the cream appears at the opening ; the quantity by which 
the milk noAV collected in the cylinder is less than the 
original 100 c.c. represents the cream, and the percentage 
of cream by A'olume can be estimated. 1"! „ by volume 
corresponds very nearly to one-fourth °|j, of butter in the 
milk, by weight. 

If a glass dish, like that described above, cannot be 
obtained, any shallow dish that can be Avell covered Avill 
answer, and the milk can be withdrawn from under the 
cream by a small siphon, w^ith a rubber tube and clamp 
at the end of the longer arm to regulate the floAV of the 
liquid. 



§ 136. MILK. 265 

Voxel's optical milk test. — This process meets with 
very general acceptance. It depends upon the fact that 
the light is intercepted by water containing a smaller 
proportion of milk, the richer the milk is in butter. 

The apparatus required consists of a measuring flask, 
with a mark on the neck, indicating a capacity of 100 c.c, 
a test-glass, for holding a sample of the milk and water 
between the eye and the light, which should have parallel 
glass sides, ^| ^ cm. apart, so that the thickness of the layer 
of milk looked through will be exactly ^ !„ cm., a pipette 
graduated in ^ \^ cubic centimetres, and holding 4-5 c.c, 
and a box about 16 cm. long and wide, with a slit in one 
side, in front of which, and 40 cm. distant, the stearin 
candle is 2:>laced ; the opposite side of this box is so cut 
out to fit the face that, when the glass containing the 
milk is put in the box, all light can be excluded while an 
observation is made, except that coming through the slit 
from the candle ; the inside of the box should be painted 
black. 

To perform the test, fill the 100 c.c. flask with distilled 
water up to the mark, add to it 3 c.c. of the well-stirred 
sample of the cooled milk, and mix the two together 
thoroughly by vigorous agitation ; fill the test-glass with 
this mixture, put it in the dark box, and make the obser- 
vation, placing the eye close to the test-glass, and the 
candle against a dark background. If the light can be 
seen, pour the test sample back into the flask, add ^ !„ c.c. 
more of milk, and make another observation ; continue to 
operate in this manner, adding ^ |„ or ^ |^ c.c. of milk each 
time, until the light is no longer visible. 

The relation between the number of cubic centimetres 
of milk required and the per cent of butter is given in 
Table IX. This per cent is calculated by the formula 
2?J _|_ 0.23, in which y = the number of cubic centimetres 
of milk required. If 5.5 c.c. or more of milk were used 
to produce opacity, it is probable that the milk was 
12 



266 § 136. FODDER AND FOOD. 

watered. It is rare that less than 3 c.c. of cow's milk will 
be needed. 

e. Sug'ar. — Collect the residue, insoluble in ether, in c?, 
on a dried and weighed filter, dry it at 100° C, boil it four 
or five times with fresh portions (150 c.c. each) of 80° j^ 
alcohol, and weigh this insoluble residue on a dried and 
weighed filter, after drying it at 100° C. The loss of 
weight, after extraction with alcohol, gives the lactose 
approximately. The residue on the filter will be mainly 
casein and insqluble salts, together with the baric sul- 
phate or gyi3sum, with which the milk was evaporated. 

Or, to determine the lactose more accurately, dilute 20 
grms. of the milk with twice its volume of water, heat 
the liquid to 40° C, coagulate the casein with 4 drops of 
acetic acid, collect the coagulum on a linen filter, and 
wash it well with water. Dilute the filtrate and washings 
to 200 c.c, and determine lactose in the usual manner, in 
a measured volume of the liquid, previously filtered if 
necessary (§ 84). 

f. Lacto-protein, butter, casein, etc. — Millon and 
Commaille give this process for estimating the protein 
compound peculiar to milk, and for the determination of 
other substances also. 

Dilute 20 grms. of milk with 4 volumes of water, add 
5-6 drops of acetic acid, stir the mixture well, filter out 
the coagulum, wash it two or three times on the filter with 
as little water as possible, and then with 40" [^ alcohol. 
Separate the precipitate from the filter, diffuse it in abso- 
lute alcohol, collect it again on a dried and weighed filter, 
and extract the butter by ether containing ^1^^ of abso- 
lute alcohol, that is poured over the contents of the filter. 
Evaporate the etherial extract, to estimate the butter taken 
into solution, and dry the casein on the filter at 100° C, 
and weigh it. 

Heat half the filtrate from the first coagulum, or the 



§ 137. BUTTER. CHEESE. 267 

whey, to boiling, filter out the coagulated cdhumen on a 
dried and weiglied filter, wash it first with water, then 
with alcohol, and finally with ether, dry it at 100° C, and 
weigh it. 

To the filtrate add a solution of mercuric nitrate, with 
care to avoid an excess of the reagent. Lacto-protein is 
2)recipitated, together with mercuric oxide; collect the 
precipitate on a weighed filter, wash it once with water 
containing l^l^, of nitric acid, then with ^wxq water as 
long as the filtrate is colored by hydrosulphuric acid, then 
with alcohol, and finally with ether; finally dry it at 100° 
C, and weigh it. 60° |g of it is to be estimated as lacto- 
protein. 

Determine milk sugar in one-fourth of the whey (§ 84). 

Evaporate the remaining fourth to dryness in a plati- 
num dish, dry the residue at 100°, and weigh it, ignite it, 
and weigh again. Subtract the ash, albumen, lacto-pro- 
tein, and milk sugar, from the total amount of matter in 
solution in the v*'hey, and call the remainder undetermined 
extractive matter. 

BUTTER. CHEESE. 

137. a. Water. — Dry 50 grms. of the finely divided 
substance at 100° C. as long as it loses weight ; butter is 
more easily dried if a weighed quantity of quartz sand 
is mixed with it. 

h. Fat. — Extract this with ether in the usual manner 
(§ 87), collecting the insoluble residue on a weighed filter. 

c. Casein. — Wash the residue, insoluble in ether, well 
with water, evaporate the aqueous solution to dryness, 
dissolve the residue again in water, and, if any of it is 
insoluble, collect this on the same filter, and wash the 
whole again; dry the contents of the filter at 100°, and 
weigh, ignite, and weigh again, and call the difference 
between the first and second weighings, casein. 



2G8 § 138. FODDER AND FOOD. 

d. Salt. — By evaporating the aqueous extract obtained 
in the preceding o^^eration, or an aliquot part of it, to dry- 
ness, and igniting and weighhig the residue, the amount 
of salt in the butter or cheese may be estimated. 

VINEGAR. 

1S8. The only constituent of vinegar which it is usually 
desired to estimate quantitatively is the acetic acid. 

a. For this estimation, proceed as directed in § 70. 
Good vinegar should contain about 5" | „ of this acid. 

The vinegar should give no reaction for sulphuric or 
hydrochloric acid, after acidification with nitric acid. If 
it has been adulterated with these acids, they will of 
course saturate a portion of the standard sodic solution. 

h. Free sulphuric acid in vinegar may be detected and 
determined by adding baric carbonate to it, filtering, 
washing the contents of the filter, and then treating the 
residue with hydrochloric acid ; the excess of baric car- 
bonate that was used will be dissolved by the acid, while, 
if any/ree sulphuric acid was present, baric sulphate will 
remain undissolved ; it may be washed and weighed in 
the usual manner (§ 59). 



§ 139. WOOL. 269 



CHAPTER IX. 

WOOL. 

139. a. The sample for examination.— Take a sample 
from each one of several sheep just before the time of 
shearing, and after the animals have been washed in the 
customary manner, and from the following parts of each 
animal — -the leaf, the side, the middle of the chine bone, 
the withers, the neck close to the nape, the middle of the 
thigh, and the middle of the belly ; each specimen should 
be taken from a spot an inch in diameter, and be cut off 
close to the skin, put at once in a large glass tube of 
known weight, that can be well stoppered, and weighed 
when taken to the laboratory. The number of the par- 
ticular animal and the spot from which the sample was 
taken should be marked on a label on each tube. 

If the Avool is to be examined with respect to its phys- 
ical properties, or by one who is experienced in handling 
it and judging its value, two other samples should be 
taken from each animal, and from the same spots, one 
before the washing, and the other afterwards, and all 
samples should be preserved and labeled in the manner 
prescribed above. 

The sample from each j^art of the animal is to be exam- 
ined by itself, but if it is desired to determine only the 
average quality of the wool of the flock, the several sam- 
ples from like parts of the different shee]) may be exam- 
ined together. 

If a sample of unwashed wool is to be examined, 
Aveigh each one, determine the Avater in a small portion 
by desiccation at 100°, and wash the other portion gently 
in cold, soft Avater until the Avater is no longer made tur- 
bid, dry it, and weigh it in the air-dried state. The 
subsequent treatment is the same as for the washed avooI. 



270 § 140. AvooL. 

h. Water. — Dry 3-4 grms. at 100° C, and weigh it. 

c. Wash a quantity of the wool in a manner similar 
to that i^racticed in the factory. For this purpose pre- 
pare a sohition of. 3 parts of hard soap and 2 of crys- 
talHzed sodic carbonate, in 100 of distilled or rain-water, 
heat 20 2:)arts of this solution to 50-55°, put 1 part of 
wool in it, and stir the mixture gently for 15 or 20 
minutes, while the solution is maintained at the same 
temperature ; then take the wool out, Avash it in several 
portions of water, dry it in the air, spread it out on fine 
wire gauze, tap the gauze gently underneath several times, 
pick off adhering particles of foreign matters with the 
pincettes, dry the residue at 100° C, and weigh it. If, 
after this treatment, the wool still feels greasy, it should 
be washed again in a somewhat stronger bath. Finally 
extract any remaining fat with carbonic disulphide or 
ether, dry the residue again at 100°, and weigh it. 

d. Treat another portion of the wool in the reverse 
manner, that is, first with ether (§ 87), and then, after 
drying and weighing the residue, wash it in the bath of 
soap and soda. Determine the fat in the etherial solu- 
tion, or an aliquot 2:>art of it. 

e. Determine the ash in the residue of c and d in the 
usual manner (§ 127). Examine this ash for sand by 
digestion with hydrochloric acid, and boiling with sodic 
carbonate (§ 58). 

f. To determine the specific gravity of the jiure wool 
obtained in c and J, weigh it first in air and then in car- 
bonic disulphide of known specific gravity (§ 35, h, d). 

TANNER'S BARK. 

140. a. Preparation of the sample. — Cut the bark to 
be examined, lengthwise, in very thin shavings. 
h. Water.— Desiccate 1-2 grms. at 100° C. 
c. Tannic acid. — ^Pour 100 c.c of water over the dried 



§ 141. WATER. 271 

substance obtained in 5, and digest the mixture in a flask, 
15 minutes at a boiling heat, filter, and repeat the same 
oj^eration twice with the resi€lue. Evaporate this aque- 
ous extract to dryness on the water-bath, with the addi- 
tion of a few drops of acetic acid, extract the residue 
with strong alcohol, filter the liquid, evaporate the filtrate 
until the alcohol is expelled, and dissolve the residue in 
distilled water; by this treatment pectose is removed 
from the aqueous extract. Determine tannic acid in the 
solution finally obtained (§ 77). 



CHAPTER X. 

BEVERAGES. 

I. 

WATER. 

141# For a complete analysis of water, we must refer 
to Fresenius's Quantitative Analysis for directions, while 
we confine ourselves here to such special determinations 
as possess a more direct domestic or agricultural interest. 

a. Total Dry Substance in Solution. — Evaporate 500 
grms. of the water to dryness, in a platinum dish, at a 
temperature at all times below boiling ; dry the residue 
at 130° C, and weigh it ; ignite it, moisten the residue two 
or three times with a concentrated solution of ammonic 
carbonate, drying it each time cautiously ; finally ignite 
the residue gently, and weigh the total non-volatile dry- 
substance. 

Or, instead of treatment with ammonic carbonate, dis- 
solve the ignited residue in water in the crucible, pass a 



2T2 § 141. BEVERAGES. 

slow current of carbonic acid through it for a while, and 
dry the residue for a considerable time at 150-180°. 

This determination of organic matter in water is con- 
sidered by some good chemists as possessing no great value. 

1). Potassai — The estimation of this in water used for 
irrigation is sometimes important. For this purpose, 
evaporate 2000-4000 c.c. of the Avater to dryness, elimi- 
nate the silica in the usual way, and the alkalies as chlo- 
rides in the filtrate from the silica (§ 93, G). 

c. Aimuonia* — To determine this in rain-water, evapo- 
rate 2000-3000 c.c. down to 200 c.c, after acidifying the 
water very slightly Avith hydrochloric acid, add an excess 
of freshly prepared sodic hydrate, or of baric hydrate, to 
the residue, and distil the ammonia oif in the usual man- 
ner (§ 47, c). 

Determine the ammonia in the distillate with the aid of 
platinic chloride, or by the indirect process with the 
Nessler solution. 

To insure greater accuracy, the whole operation should 
be repeated without the water, and with the same amount 
of sodic or baric hydrate and platinic chloride or Nessler's 
solution ; if any ammonia is thus found, it is due to im- 
purities in the reagents, and should be subtracted from 
the amount obtained in the first experiment. 

If the water is a colored one, derived from some other 
source, add calcic chloride, sodic carbonate, and a few 
drops of potassic hydrate before distilling. 

d. Nitric Acid. — Evaporate 2000-4000 c.c. of the water, 
after having added some sodic carbonate, filter out the 
precipitate, if any is formed, wash it well, evaporate the 
filtrate and washings to a small bulk, and determine the 
acid by Schlossing's j^rocess (§ 62, a). 

e. Organic Matter. — Evaporate 100 c.c. of the water 
down to about 60 c.c, in a flask of 500 c.c. capacity, in 
order to decompose ammoniacal compounds by the calcic 



§ 141. WATER. 273 

carbonate that is nearly always present, add water till 
the original volume is about restored, and proceed to 
titrate the solution for the organic matter with i:>otassic 
permanganate (§ 91). 

A good drinking water should not contain more than 
3-4 parts of organic matter in 100,000 parts. 

If, on adding to 100 c. c. of the water 2 or 3 drops of 
concentrated sulphuric acid and a little of a freshly pre- 
pared mixture of potassic iodide and boiled starch, the 
water is colored blue, nitrous acid is present, and a correc- 
tion must be made in the determination of the organic 
matter. For this purpose add 10 c.c. of the dilute sul- 
phuric acid to 100 c.c. of the water, and then add per- 
manganic solution till the first trace of a red color appears. 
The amount of the standard solution required for this 
must be subtracted from the total amount required in the 
first trial. 

The presence of nitrous acid in drinking water should, 
however, be regarded with suspicion, for it indicates that 
the water, perhaps, contained nitrogenous organic matter, 
from which it may not yet be entirely freed ; such organic 
matter is far more harmful than that containing no nitrogen. 

Other prominent methods of making this important 
determination of organic matter, and particularly nitrog- 
enous matter, in water, have not yet been sufficiently 
tested to justify their insertion here, although, without 
doubt, good methods will soon be worked up out of the 
material now in hand. Many good chemists still allow 
some value to the indications that are furnished by the 
permanganic test relative to the badness of the water in 
sanitary respects, while others have no confidence in it. 
Other substances besides nitrous acid may increase the 
amount of permanganic solution that is reduced, and so 
give too large an amount of organic matter, as ferrous sul- 
phate, for instance. 

f. Lime* — To determine this base, which, in one form or 
12* 



274 § 141. BEVERAGES. 

another, is tho source of the largest part of the hardness 
of water, add a little hydrochloric acid to 100-500 c.c, 
heat the mixture, and precipitate and determine lime with 
the aid of ammonic oxalate, in the usual manner (§ 49, a). 

Or, by a more speedy though somewhat less accurate 
method, to 100 c.c. of the water in a 300 c.c. flask, add 
25 c.c, or, if the water is very hard, 50 c.c. of a ^ 1^^ atomic 
solution of oxalic acid, then add ammonia until the 
reaction of the liquid is faintly alkaline, and heat the 
mixture until it boils. 

After the liquid has cooled, add distilled water up to 
the 300 c.c. mark, mix the whole well together, filter the 
liquid through an unmoistened filter into a dry glass, 
putting the first portions of the filtrate on the filter again, 
if turbid, as is often the case. To 200 c.c. of the clear 
filtrate, in a caj^acious flask, add 10 c.c. of concentrated 
sulphuric acid, heat the solution to 50-60° C, and deter- 
mine the excess of oxalic acid in it with the aid of the 
standard permanganic solution (§ 69). By multiply- 
ing the number of cubic centimetres of the standard 
solution used by 1.5, the amount that would have been 
required for the whole solution is obtained. Each cubic 
centimetre of the solution of oxalic acid that did not 
require to be decomposed by the permanganate, Avas 
engaged in the precipitated calcic oxalate, and corre- 
sponds to 0.0028 grm. of lime. 

(/. Hardness of the Water. — 1. Clark's method. This, 

thou2rh a convenient method of determininiT; the hardness 
of water, does not give highly accurate results ; it is, 
however, generally used. 

The scale of hardness is expressed by the number of 
milligrammes of lime in 100,000 mgrs., or 100 grms. of 
water, that are required to produce the cjilFerent degrees 
of hardness, and this hardness is estimated by the amount 
of soajo precipitated from a standard solution of the 
same. 



§ 141. WATEK. 275 

The Standard Solution of Soap. — Mix tagether 150 
parts of lead plaster and 40 parts of potassic carbonate, 
exhaust the mass with alcohol, filter the liquid, evaporate 
the filtrate on the water-bath, and dissolve the residue in 
50 parts of 56" |„ alcohol. Dissolve, also, 0.523 grm. of 
pure and dry baric chloride in water, and dilute the solu- 
tion to one litre. 

Provide a bottle of about 200 c.c. capacity, with a well- 
fitting glass stopper, and a mark on the side to indicate a 
capacity of 100 c.c, put 100 c.c. of the solution of baric 
chloride in this bottle, and add the solution of soap from 
a burette or a graduated pipette, with frequent agitation, 
until an abundant delicate lather appears that lasts Jive 
minutes. The shaking of the bottle should always be 
performed in the same manner ; the best Avay is to grasp 
the stopper and the neck with one hand, and the bottom 
with the other, and shake it up and down. 

Having tested the strength of the solution of soap, 
dilute it with 56° |g alcohol to such an extent that 45 c.c. 
are necessary to produce the lather with 100 c.c. of the 
solution of baric chloride ; this quantity of the latter 
solution produces the same degree of hardness as 12 
m^rs. of lime. 

Examination of a Sample of Water. — If a hard spring 
water is to be examined, put 10 c.c. of it into the bottle 
described above, and add distilled water up to the 100 c.c. 
mark ; if it is a soft river water, fill the bottle up to this 
mark with the water alone ; then add the solution of soaj) 
from the burette, as above. Add at first larger quantities of 
the standard solution at a time, but, toAvards the close, 
the agitaiion should be repeated after each 0.5 or 1 c.c. 
that is added, and finally between each drop or two. 

On repeating the experiment, in case but little of the 
standard solution was used, take 25 to 50 c.c. of the water, 
but not a quantity that will require more than 45 c.c. of 
the standard solution ; in this second trial add, at once, 



276 § 141. BEVERAGES. 

all but 1-2 c.c. of the solution of soap that will be 
required, and then allow it to flow in drop by drop only, 
until the reaction is ended. 

The relation between the quantity of the standard solu- 
tion used and the hardness of the water is given in Table 
VIII. If the water tested was diluted with distilled water, 
the hardness is to be taken as many times greater as the 
volume of the water was increased by the dilution. 

If a water contains more than 12 parts of lime in 
100,000, the first addition of the solution of soap to it 
causes the formation of a flocculent precipitate, and it 
must be diluted as above before the test is made ; if less 
than this proportion of lime is present, only an opalescence 
appears in the liquid on adding a drop of the solution of 
soap. 

"VYith respect to the hardness of water, we have to dis- 
tinguish the total hardness, which is caused by the total 
amount of lime in the water, and the permanent hardness, 
causexl by salts of lime that are not precipitated when the 
liquid is boiled, such as calcic sulphate and chloride. To 
determine this permanent hardness, boil 300 to 500 c.c. of 
the water half an hour, in a flask of twice the capacity, 
rej)lacing the water, as it is evaporated, by fresh distilled 
water ; after the liquid has cooled, make its volume the 
same as that with which the operation was begun, by 
adding more water, mix the whole w^ell together, filter 
the liquid, and determine the permanent hardness in an 
aliquot part of it, as above. 

2. FlecVs method. — This apparently convenient method 
depends upon the fact that, w^hen a solution of soda-soap 
in alcohol is added to a solution of a calcic salt, a neutral 
sodic salt is formed, and that, as soon as all the calcic salt 
is decomposed, the addition of more soda-soajD will turn 
red litmus blue. {Freeenius'^ s Zeitschrift, 7, 351.) 

The Standard Solutions.— Solution of Soap. — Cut 50 



§ 141. -WATER. 277 

grms. of pure Marseilles soaj^ in thin slices, pour 500 c.c. 
of 74" |g alcohol over it, and heat the mixtures ; the soap 
should be free from sodic carbonate or hydrate, and its 
solution should, therefore, give no precipitate or black 
color with mercurous nitrate. Filter the solution, if it is 
not perfectly clear. Prepare a saturated solution of calcic 
sulphate, and to 100 c.c. of it add 10 drops of a solution 
of litmus (or cochineal) ; boil the liquid five minutes and 
add the standard nitric acid from a burette, drop by drop, 
until the blue color is changed to red ; then add the solu- 
tion of soap from another burette until the blue color 
reappears. 

The solution of soap is now to be made of such a 
strength that 20 c.c. of it will be required to produce the 
blue color, with 100 c.c. of the solution of calcic sulphate. 
If, for example, 15 c.c. were required in the above experi- 
ment, 5 c.c. of alcohol must be added to every 15 of the 
solution of soap to make the standard solution. 

100 c.c. of the saturated solution of gypsum contain 
210 mgrs. of calcic sulphate ; each cubic centimetre of 
the soap solution, representing 1° of hardness, corre- 
sponds, therefore, to 12 mgrs. of calcic siilphate. 

The standard nitric acid is conveniently made of such 
a strength that 0.1 c.c. neutralizes 1 c.c. of the standard 
solution of soap. 0.05 c.c. of nitric acid, corresponding to 
0.5° of hardness, has to be used in excess to produce a 
permanent red ; therefore, 0.5 should be subtracted from 
the total amount of soap solution used. 

Examination of a Sample of Water. — If the water 
contains calcic carbonate, boil 100 c.c. in a beaker or 
llask, until the carbonate is precipitated ; then, without 
filtering, add 10 drops of litmus solution (or cochineal), 
and add the nitric acid precisely as in estimating the 
strength of the solution of soap, as first made; the litmus 
will not be colored permanently red until all the calcic 
carbonate is dissolved ; therefore, the number of cubic 



278 § 142. BEVERAGES. 

centimetres of acid required for this represents the tem- 
porary hardness. After adding the proper quantity of 
nitric acid, j^roceed to add the standard solution of soaj), 
in the same manner as when determining the strength of 
this solution with the aid of calcic sulphate. 

Suppose that, in treating 100 c.c. of the water in this 
manner, 0.2 c.c. of nitric acid were required to produce a 
permanent red color, and 8 c.c. of the solution of soap to 
change the red to blue ; 2 c.c. of the latter were necessary 
to decompose the calcic nitrate resulting from the action 
of the 0.2 c.c. of nitric acid on the calcic carbonate, and 
6 c.c. to decompose the calcic sulphate; subtracting 0.5 
c.c, as above directed, for the excess of nitric acid, we 
have 2° for the temporary hardness, and 5.5° for the j^er- 
manent hardness of the water examined. 

10° of hardness indicates a hard water; the hardness of 
river water is usually from 2° to 6°. 

II. 

WINE. 

142. a. Specific Gravity. — Determine this carefully 
with the S]3ecific-gravity bottle. 

h. Dry Substance in Solution. — Evaporate 20 grms. 
to dryness with gypsum (§ 90, h). 

c. Total Non-volatile Matters.— Evaporate 200-500 
grms. to dryness on the water-bath, and incinerate the 
residue in the usual man;ier ; determine carbonic acid in 
the ash. 

cl Complete Analysis of the Ash.— This is rarely im- 
portant, but may be made according to Scheme I., § 94. 

e. Protein Compounds. — Evaporate 100 grms. with 
gypsum (§ 90, A), and ignite the residue with soda-lime 
(§ 85). 



§ U2. WINE. 279 

f. Alcohol* — Estimato this in 10 or 25 c.c. of the wine, 
adding a few drops of soda, or enough to change the 
color of the wine completely, and about 0.06 grm. of 
tannin ; the soda neutralizes the free acid, and the tannic 
acid prevents frothing. For the manner of conducting 
the distillation, see § 87. 

(/. Su^ar. — This may be determined in 100 grms. of 
the wine directly, in the usual manner (§ 81), after decol- 
orizing the liquid by contact with 2-3 grms. of bone-black, 
and filtering. 

Or, the wine may be decolorized in this manner 
(Griffin). Dilute the red wine to about half the extent 
required for the determination of sugar, add enough milk 
of lime to make the liquid alkaline, and agitate the mix- 
ture well ; then add about one-tenth as much of a solution 
of basic plumbic acetate as was taken of the wine, and 
shake the mixture again ; finally add one-third as much 
of a solution of alum, containing 1 part of salt in 20 of 
water, as was required of the plumbic solution, dilute the 
mixture to any volume easily divisible into aliquot parts, 
mix the whole together by violent agitation, let it stand 
until the solid matters settle, and then decant enough of 
tlie supernatant liquid into a dry filter for the determina- 
tion of the sugar. 

If the wine is a light-colored one, nothing need be 
added but sodic carbonate until it is alkaline. 

Cane sugar exists in wine only when it has been pur- 
posely added. It can be estimated, if present, in the 
usual way (§ 83). 

If the wine is neutralized with lime, and alcohol added 
to precipitate malic and succinic acids, a little baryta- 
water will give a precipitate in the filtrate, which is more 
or less abundant, according to the amount of sugar pres- 
ent (§ 83). 

h. Gum (and sugar) , etc.— Evaporate 100 grms. of the 
wine to a syrup on the water-batli, exhaust the residue 



280 § 142. BEVERAGES. 

by digestion with several portions of alcohol, as long as 
a fresh portion is colored, and estimate the gum in the 
insoluble residue as directed in § 80. 

Half of the alcoholic extract may be evaporated to 
dryness, the residue weighed, and tlien incinerated, and 
the ash weighed; thus the total volatile and non-volatile 
(organic and inorganic) matter, soluble in alcohol^ may be 
estimated. 

Sugar may be determined in the other half of the alco- 
holic extract, after adding water and heating the liquid 
on the water-bath until all the alcohol is expelled (§ 81). 

^. Tannic acid. — This acts upon the cupric solution, 
used in determining sugar, precisely as sugar does, 3.7 
parts reducing as much cupric oxide as 5 parts of sugar. 
Tannic acid is absorbed when the wine is decolorized by 
contact with bone-black ; the difference, then, between the 
amount of cupric solution required with and without 
treatment with bone-black, will give, approximately, the 
amount of tannic acid. But in many cases the wine would 
be too dark-colored to admit of a determination of sugar 
by the cuj^ric solution without treatment with the decol- 
orizing agent, and there are, moreover, other substances 
in the wine that are removed by the charcoal, and that, 
at the same time, act on the cupric solution. When, how- 
ever, the determination can be made, it answers very 
well for the comparison of different wines with each 
other, since the proportion of the other reducing agents 
does not seem to vary much. 

h. Free acids. — Titrate 100 grms. of the wine with the 
standard sodic solution. 

Then mix another portion of 100 grms. with clean sand, 
and evaporate it to dryness on the water-bath, with con- 
stant stirring, and heat it as long as any odor of acetic 
acid is evolved ; dissolve the residue in water, and titrate 
the solution with the standard sodic solution. The dif- 



§ 142. WINE. 281 

ference between the amounts of soclic solution required in 
the two trials represents the acetic acid. 

Estimate 0.06 grm. of acetic acid, HC^HjO^, for every 
cubic centimetre of this difference, and 0.075 grm. of tar- 
taric acid, Ji.CJrlfi^, for every cubic centimetre of the 
sodic solution required after the acetic acid was expelled. 

Griffin ( Chemical Testing of Wines and Spirits) deter- 
mined the free acid as follows, with a ^ 1^^ atomic solution 
of ammonia for the standard solution, and an extract of 
logwood for the coloring matter. 

Take two portions of wine, of "T.S c.c. each, and add to 
each, if it is a white wine, 125 c.c. of water, or, if it is a 
red wine, 250 c.c, or more, according to the depth of the 
color ; then add exactly the same quantity of the extract 
of logwood to each portion, which gives a color to the 
wine very much like that obtained by painting paper 
with raw sienna; add the alkalipe solution from the 
burette to one j^ortion, keeping the other at hand for 
comparison, with constant stirring ; when the color sud- 
denly changes to a reddish-brown, like that obtained by 
burnt sienna on paper, the point of saturation is reached, 
l^ow, repeat the experiment with the other portion of the 
wine, adding all but 2-3 c.c. of the required quantity of 
standard ammonic solution at once, and then drop by 
drop, until the acid is saturated. 

Each cubic centimetre of the alkaline solution required 
corresponds to 0.1 of an equivalent of free acid, or, if we 
call it all tartaric acid, as it is, mostly, 0,0075 grm ; and 
in this case the number of cubic centimetres used gives 
at once the number of grammes of acid (tartaric) in the 
litre of wine. 

Good wines contain 4-6 grms. of free acid in the litre 
(300-400 grains of crystallized tartaric acid, Griffin). In 
poor wine years, the proportion of free acid often rises 
as high as 10-12 grms. in the litre. 

I Tartar.— Add 40 c.c. of 90°|„ alcohol to 20 c.c. of 



282 § 142. UEVERAGES. 

the Yfine, let the mixture stand several days in a well- 
closed bottle, and then titrate 30 c.c. of the clear liquid 
with the standard sodic solution ; subtract 0.3 c.c. from 
the amount of soda required, and then subtract this re- 
mainder from the amount that would be required, as in 
^, to neutralize the total free acid in 10 c.c. of wine ; this 
second remainder represents the quantity of acid that was 
removed from the wine by treatment with alcohol ; for 
each cubic centimetre of this remainder calculate 0.1881 
grm. of tartar. 

Griffin estimated tartar by evaporatmg 100-200 c.c. of 
the wine to dryness, incinerating the residue, determining 
potassic carbonate in the ash with the aid of the standard 
acid, and allowing one equivalent of tartar for every 
equivalent of i:)otassic carbonate thus found in the ash. ] 

He estimated it also by adding 25 c.c. of alcohol and - 
as much ether to 10 c.c. of wine, letting the mixture 
stand 24 hours, collecting the precipitate on a dried and 
weighed filter, drying it at 100° C, and weighing it ; 
all but about 0.002 grm. of the tartar will be precipitated 
in this way. 

m. Total tartaric acid. — Evaporate 100 c.c. of the wine 
to about half its volume, precipitate the acid by lime- \ 
water in slight excess, filter the 23recipitate out, boil it 
with a solution of potassic carbonate, filter the liquid, 
evaporate the filtrate somewhat, acidify it with acetic acid, 
precipitate the potassic tartrate with considerable alcohol, 
and collect and treat the precipitate as directed in § 71. 

n. Malic acid, — This is contained in the filtrate from 
the calcic tartrate in m. To determine it, evaporate this 
filtrate down to one-third, and precipitate the calcic malate 
with alcohol, as directed in § 73. As this precipitate will 
contain also the sulphuric acid, if any is j^resent in the 
wine examined, a determination of this acid should be 
made in a portion of the wine, in the usual manner ; then 
estimate the amount of calcic sulphate, CaSO^, 2Hfi, in 






§ 142. WINE. 283 

the precipitate obtained as above with alcohol ; the re- 
mainder, after subtracting this, may be reckoned as calcic 
malate, although it may contain a little succinate. 

The acetic acid, malic acid, and tartar, taken together, 
correspond very nearly to the amount of soda used in /:, 
to determine the free acid, each equivalent of tartar neu- 
tralizing one equivalent of soda. 

o. Free sulphuric acid, if present in the wine under 
examination, may be detected and determined in the same 
manner as directed in § 138, b. 

p. Total alkalies. — These may be estimated in the ash 
obtained in c, or in the following manner. 

To the remaining 30 c.c. of the filtrate from the pre- 
cipitate by alcohol in /, add 5 c.c. of an alcoholic solution 
of tartaric acid, whose strength is accurately known, let 
the mixture stand several days, and titrate 25 c.c. of the 
clear supernatant liquid with the standard sodic solution ; 
the rest of the potassa, not precipitated in I, and the soda, 
have crystallized out, w^ith an equivalent quantity of the 
tartaric acid that was added ; this quantity of acid will be 
represented by the difference between the amount of sodic 
solution used in this trial, and that Avhich would be re- 
quired to neutralize the free acid already in the solution 
(see I), plus the 5 c.c. of tartaric acid added. For each 2 
c.c. of this difference estimate 0.0471 grm. of potassa and 
add it to the amount in the tartar obtained in I. 

The average composition of v,'ine, according to IsTessler, 
who examined a large number of European wines, is as 
follows: Alcohol, T- 10° 1^; Sugar, 0.1 - 0.2" |„; Free acid, 
estimated as tartaric, 0.4 _ 0.8°| „ ; Malic acid, - 0.3° |„ ; 
Acetic acid, 0-0.3°|^; Tannic acid, 0.02 - 0.05"! „. 
Total dry substance in solution, 1.5 — 2"!^. 



284 



TABLES. 



TABLE I. 

THE METRIC SYSTEM OF WEIGHTS AND MEASURES. 



1. 
Measures of Length. 

1 Metre = 1 Metre. . — ^ 

1 Decimetre = 0.1 " 

1 Centimetre = 0.01 «' 

1 Millimetre = 0.001 " 

1 Metre = 39.37 Inches. 

1 Centimetre = 0.3937 Inch. 

1 Foot = 30.48 Centimetres. 

1 Inch = 25.4 Millimetres. 

The accompanyiuir scales, copied from Professor 
H. A. Newton's little pamphlet (The Metric 
System of Weiuhts and Measures, with Tables. 
Prepared for the Smithsonian Institution), ex- 
hibit the relative maj^nitude of the divisions of 
the metre and inches. 



Measures of Volume, 



1 Cubic metre 



= 1000. 



.Litres. 



1 Cubic decimetre = 
1 Cubic centimetre =r 
1 Cubic centimetre = 
1 Litre = 

1 Gallon (imperial) = 
1 Gallon (wine) = 
1 Hectolitre = 



1. Litre. 

0.001 Litre. 

0.06103 Cubic Inch. 

0.88066 Quart. 

4.5435 Litres. 

3.79 Litres. 

2.84 Bushels. 



3. 



The Weights of the Metric System. 
1 Kilogramme 
1 Hectogramme 
1 Decagramme 
1 Gramme 
1 Decigramme 
1 Centigramme 
1 Milligramme 
1 Kilogramme 
1 Gramme = 0.0353. Ounce 

1 " = 15.433 Grains. 

1 Pound = 453.6 Grammes. 

1 Ounce = 28.3 '* 

1 Grain = 64.8 Milligrammes. 

4. 
Abbreviations. 



1000 

100 


....G 


rammes. 


10 






1 

0.1 


....Gi 


•am me. 


'O.OL 






0.001 .. 






2.2046. P'ds 


(avoir 


dupois.) 






"■^ 




— 


_ 










— 


— " 




J , — 










= 













— 






K. — 








—, 




— 




-r» 







. — 


-~ 






nz: 


— 




— 


— 




^fk 








- 











:zz: 


— 




M 




-ro 









— 




^ 


— 




o> — r= 


- 




— 






: — 


— 




" — 






— 


— 










— 


— 






— 






— - 


— 












— 














rf^ 





Centimeti-e 

Millimetre 

Cubic centimetre. 

Kilogramme 

Gnimme 

Milligramme 



.Cm. 
Mm. 

.C.c. 



.Kilo. 
,Grm. 
. Mgr. 



TABLES. 



285 



TABLE 11. 



THE ATOMIC WEIGHTS OF THE ELEMENTS CONCERNED IN 
THE QUANTITATIVE PROCESSES DESCRIBED IN THIS BOOK. 



AluQiinium, Al 27.5 

Barium, Ba 137.0 

Calcium, Ca 40.0 

Carbon, C 12.0 

Chlorine, CI 35.5 

Copper, Cu 63.5 

Iron, Fc... 56.0 

Magnesium, IMg 24.0 

Manganese, Mn 55.0 



Nitrogen, N 14.0 

Oxygen, 16.0 

Phosphorus, P 31.0 

Platinum, Pt 197.1 

Potassium, K 39.1 

Silicon, Si 2S.0 

Silver, Ag 108.0 

Sodium, Na 23.0 

Sulphur, S 32.0 



TABLE III. 

FACTORS FOR ESTIMATING THE SUBSTANCE SOUGHT 
FROM THE COMPOUND OBTAINED. 



Compound 
obtained. 


Formula. 


Substance sought. 


Formula. 


Factor. 




AI2O3 


Clay 


AI2O3. 2Si02 








2H2O 


2.5150 


Ammonia 


NH3 


Nitrogen 


N 


0.8235 


Ammonio -platin- 










ic chloride 


(NH4).PtCl6 


\mmonia . 


NH3 


0762 


Ammonio -platin- 








ic chloride 


(NHO.PtCle 


Ammonic oxide. 


(NH4),0 


0.1165 


Ammonio -platiu- 










ic chloride 


(NH4)2PtCl6 


Nitrogen 


N 


0.0628 


Argentic chloride 


AgCl 


Chlorine 


CI 


0.2474 


Argentic sulphide 
Baric sulphate. .. 


A'o-S 


Sulphur . ... 


s 


1481 


BaS04 


Sulphuricanhy- ) 
dride ] 


S03 


0.3433 


U C( 


CaCOs 


Sulphur 


s 

Ca 


1373 


r^nlr'lp nirbnmtp 


Calcium 


0.4000 






Calcic oxide ) 
(lime) i 










CaO 


0.5600 






Calcic Bulpliate 










(cryst ) 


CaS04,2H20 


1.7200 


Calcic malate 


CaC4H405 


Malic acid 


H2C4H4O5 


0.7791 


(k u 




Malic anhydride. 


C4H4O4 


0.6744 


Calcic sulphate. . 


CaS04 


Calcic oxide ) 
(lime) [ 


CaO 


0.4118 


Carbonic acid 


CO., 


Calcic Carbonate. 


CaCOa 


2.2730 


u u 


" 


Calcic hydrate.. . 


CaHoOa 


1.6820 


" " . . • . 


u 


Humus 




0.4702 



286 



TABLES. 



TABLE llL—{Co}itinited.) 



Coiupouucl 










obtained. 


Formula. 


Substance sought. 


Formula. 


Factor. 


Ferric oxide 


FCaOg 


Ferrous oxide.. . 


FeO 


0.9000 


(( u 


FcaPaOg 


Iron 


Fe 
Fe 


7000 


Ferric pliospliate. 


Iron 


5298 




Phosphoric an- ) 
hydride f 










P.O5 


0.4702 


Ferrous oxide... 


FeO 


Ferric oxide 


FCsOg 


1.1110 


a u 


Ci2H"40i2 


Iron 


Fe 


7780 


Glucose 


Saccharose 


9500 






Starch 




9000 


Lactic anhydride. 


CellzoOs 


Lactic acid 


H^CeHioOe 


1.1110 


Maunesic pyro- 










phospliate 


M-2P20, 


Magnesic oxide.. 


MgO 


0.3604 


Mao:nesic pyro- 




Phosphoric anhy- 






pbospliate 

Magnesic pyro- 


MgaP^Or 


dride . . 


P2O5 


6396 


Tricalcic phos- 




phosphate 

Mani^auous mau- 


MgoPaOy 


phate 


CaaPr.Os 


1.3960 










ga'nic oxide IMusOi 


Manganous oxide 


lAInO 


0.9301 


Mano-anous man- 










o-auic oxide 


Mn304 


Manganic oxide. 


MngOg 


1.0350 


Nitrogen 


N 


Ammonia 

Protein com- ] 
pounds f 


NH3 


1.2140 












6.2500 


Pliosphoric anhy- 




Tricalcic phos- 






dride 


P2O5 


phate 


CagPsOe 

NH3 

K 


2 1830 


Platinum 


Pt 




1725 




Potassium 


0.3968 


Potassic chloride. 


KCl 


Potassium 


K 


0.5241 


u u 


" 


Potassic oxide.. . 


K2O 


0.6314 


Potassic oxide 




Potassa feld- ( 
spar ] 


K2O, SSiO., 


5.9150 


(potassa) 


KoO 


AI2O3, SSiOs 


Potassic sulphate K2SO4 


Potassium 


K 


0.4489 




" 


Potassic oxide.. . 


KoO 


0.5408 


Potassic tartrate. 


KHC4H4O6 


Tartaric anhy- ) 
dride |" 


C4H4O5 


0.7018 


u a 


" 


Tartaric acid 


H2C4H4O6 


0.7974 


Potassio - platinic 










chloride 


K^PtCla 


Potassium 


K 


0.1602 


Potassio- platinic 










chloride 


KaPtCla 


Potassic oxide. . . 


K2O 


0.1929 


Potassio - platinic 










chloride 


KsPtCle 


Potassic chloride. 


KCl 


0.3055 


Sodic chloride.. . 


NaCl 
(I 




Na 
Na20 


. 3932 


U (( 


Sodic oxide 


0.5299 


Sodic oxide (soda) 


NaoO 


Soda feldspar. . | 


NaaO, SSiOa 
AI2O3, SSiOs 


8.4680 


Sodic sulphate. . . 


NaoS04 


Sodium 


Na 
NasO 


3239 


Sodic oxide 


0.4366 


Sulphuric anhy- 










dride. ........ 


SO3 


Tartaric acid 


H2C4H40e 

KHC4H40fl 


1 8750 


Tartaric acid 


H2C4H40e 


Tartar 


1.2540 



TABLES. 



287 



TABLE IV. 



ESTIMATION OF TANNIC ACID IN BARK. 



Sp. Gr. at 


"loOf 


Sp. Gr. at 


« lo of 


Sp. Gr. at 


°|oof 


Sp. Gr. at 


«|o of 


15° C. 


taunic 


15° C. 


tannic 


15° C. 


taunic 


15° C. 


taunic 




acid. 




acid. 
1.6 




acid. 




acid. 


1.0000 


0.0 


1.0064 


1.0134 


3.1 


1.0188 


4.7 


1.0004 


0.1 


1.0008 


1.7 


1.0128 


3.3 


1.0192 


4.8 


1.0008 


0.3 


1.0072 


1.8 


1.0133 


3.3 


1.0196 


4.9 


1.0013 


0.3 


1.0076 


1.9 


1.0136 


3.4 


1.0301 


5.0 


1.0016 


-0.4 


1.0080 


3.0 


1.0140 


3.5 






1.0020 


0.5 


1.0084 


3.1 


1.0144 


3.6 






1.002-i 


0.6 


1.0088 


3.3 


1.0148 


3.7 






1.00,38 


0.7 


1.0092 


3.3 


1.0152 


3.8 






1.0032 


0.8 


1.0096 


3.4 


1.0156 


3.9 






1.0036 


0.9 


1.0100 


2.5 


1.0160 


4.0 






1.0040 


1.0 


1.0104 


3.6 


1.0164 


4.1 






1.0044 


1.1 


1.Q108- 


2.7 


1.0168 


4.2 






1.004S 


1.3 


1.0113 


3.8 


1.0172 


4.3 






1.0052 


1.3 


1.0116 


3.9 


1.0176 


4.4 






1.0056 


1.4 


1.0120 


3.0 


1.0180 


4.5 






1.0060 


1.5 






1.0184 


4.6 







TABLE Y. 

PROPORTION BY WEIGHT OF ABSOLUTE ALCOHOL IN SPIRITS 
OF DIFFERENT SPECIFIC GRAVITIES AT 15.5° C. (FOWNES.) 



Sp. Gr. 


°lo 


Sp. Gr. 


lo 


Sp. Gr. 


lo 


Sp. Gr. 


°|o 


0.9991 


0.5 


0.9803 


13 


0.9638 


26 


0.9416 


39 


0.9981 


1 


0.9789 


14 


0.9633 


27 


0.9396 


40 


0.9965 


3 


0.9778 


15 


0.9609 


28 


0.9376 


41 


0.9947 


o 


0.9766 


16 


0.9593 


29 


0.9356 


42 


0.9930 


4 


0.9753 


17 


0.9578 


30 


0.9335 


43 


0.9914 


5 


0.9741 


18 


0.9560 


31 


0.9314 


44 


0.9898 


6 


0.9738 


19 


0.9544 


33 


0.9293 


45 


0.9884 


7 


0.9716 


20 


0.9538 


33 


0.9370 


46 


0.9869 


8 


0.9704 


31 


0.9511 


34 


0.9349 


47 


0.9855 


9 


0.9691 


23 


0.9490 


35 


0.9338 


48 


0.9841 


10 


0.9678 


23 


0.9470 


36 


0.9206 


49 


0.9838 


11 


0.9665 


24 


0.9453 


37 


0.9184 


50 


0.9815 


12 


0.9653 


25 


0.9434 


38 







288 



TABLES. 



TABLE VI. 

ESTIMATION OF SUGAR AND TOTAL DRY SUBSTANCE IN THE 
SUGAR BEET, BY THE SPECIFIC GRAVITY OF THE BEET. 



Sp. Gr. 


"lo 


Total 


Sp. Gr. 


1o 


Total 


Sp. Gr. 


."'o 


Total 


at 


Sugar. 


dry eiib- 


at 


Sugar. 


dry sub- 


at 


Sugar. 


dry sub- 


18° C. 




stauce. 


18° C. 




stance. 


18° C. 




stance. 


1.014 


7.00 


12.0 


1.038 


11.00 


17.3 


1.060 


13.75 


20.25 


1.016 


7.50 


12.5 


1.040 


11.25 


17.6 


I 1.062 


14.00 


20.50 


1.018 


8.00 


13.0 


1.042 


11.50 


18.0 


i 1.064 


14.25 


20.75 


1.020 


8.25 


13.5 


1.044 


11.75 


18. *5 


1.066 


14.50 


21.00 


1.023 


8.75 


14.0 


1.046 


12.00 


18.5 


1.068 


14.75 


21.25 


1.024 


9.00 


14.5 


1.048 


12.25 


18.75 


1.070 


15.00 


21.50 


1.026 


9.50 


15.0 


1.050 


12.50 


19.00 








1.028 


9.75 


15.5 


1.052 


12.75 


19.25 








1.030 


10.00 


16.0 


1.054 


13.00 


19.50 








1.032 


10.25 


16.3 


1.056 


13.25 


19.75 








1.034 


10.50 


16.6 


1.05S 


13.50 


20.00 








1.036 


10.75 


17.0 















TABLE YIL - 

ESTIMATION OF STARCH AND TOTAL DRY SUBSTANCE IN 
POTATOES, BY THE SPECIFIC GRAVITY OF THE TUBER. 



Sp. Gr. 




Total 


Sp. Gr. 




Total 


Sp. Gr. 




Total 


at 


Starch. 


dry sub- 


at 


Starch. 


dry sub- 


at 


Starch. 


dry sub- 


18° C. 




stance. 


18° C. 




stance. 


18° C. 




stance. 


1.060 


9.54 


10.96 


1.082 


14.50 


22.07 


1.106 


20.13 


37.86 


1.062 


9.98 


17.41 


1.084 


14.96 


22.54 


1.108 


20.61 


38.36 


1.064 


10.42 


17.87 


1.0S6 


15.42 


23.03 


1.110 


21.09 


38.86 


1.066 


10.87 


18.33 


1.088 


15.88 


23.50 


1.112 


21.57 


39.35 


1.088 


11.32 


18.79 


1.090 


16.35 


23.98 


1.114 


22.05 


39.85 


1.070 


11.77 


19.26 


1.092 


16.81 


24.46 


1.116 


33.54 


30.35 


1.072 


12.22 


19.72 


1.094 


17.28 


24.94 


1.118 


23.03 


30.85 


1.074 


12.67 


20.18 


1.096 


17.75 


25.42 


1.120 


23.53 


31.36 


1.076 


13.12 


20.65 


1.098 


18.23 


25.91 


1.122 


24.01 


31.86 


1.078 


13.58 


21.13 


1.100 


18.70 


26.40 


1.124 


34.50 


33.36 


1.080 


14.04 


21.60 


1.102 


19.17 


26.88 


1.126 


34.99 


33.87 








1.104 


19.65 


27.37 


1.128 
1.130 


35.49 
35.99 


33.33 
33.90 



TABLE IX. 

HARDNESS OF WATER. 



C.C. of 


Hard- 


C.C. of 


Hard- 


C.C. of 


Hard- 


C.C. of 


Hard- 


soap 


ness or 


soaj) 


ness or 


soap 


ness or 


soap 


ness or 


solution 


M-r. 


solution 


Mgr. 


solution 


Msrr. 


solution 


Mgr. 


used. 


CaO. 


used. 


CaO. 


used. 


CaO. 


used. 


CaO. 


3.4 


0.5 


15.1 


3.5 


26.3 


6.5 


36.7 


9.5 


5.4 


1.0 


17.0 


4.0 


38.0 


7.0 


38.4 


10.0 


7.4 


1.5 


18.9 


4.5 


39.8 


7.5 


40.1 


10.5 


9.4 


3.0 


30.8 


5.0 


31.6 


8.0 


41.8 


11.0 


11.3 


3.5 


33.6 


5.5 j 


33.3 


8.5 


43.4 


11.5 


13.3 


3.0 


24.4 


6.0 


35.0 


9.0 


45.0 


13.0 



TABLES. 



289 



TABLE VIII. 

PER CENT OF BUTTER IN MILK, BY VOGEL'S OPTICAL MILK 

TEST. 



C.C. of 

milk re- 
quired. 

2.50 
2.75 
3.00 
3.25 
3.50 
3.75 
4.00 
4.25 



O|o0f 

butter. 



9.51 
8.73 
7.96 
7.41 
G.S6 
0.44 
G.03 
5.70 



C.C. of 

millc 
used. 



4.50 
4.75 
5.00 
5.25 
5.50 
5 . 75 
6.00 
6.25 



°lo of 
butter. 



C.C. of 

mi lie 
used. 



6.50 
6.75 
7.00 
7.25 
7.50 
7.75 
8.00 
8.25 



"loof 
butter. 



3.80 
3.66 
3.54 
3.43 
3.32 
3.22 
3.13 
3.04 



C.C. of 


^lo of 


milk 


butter. 


used. 




8.50 


2.96 


8.75 


2.88 


9.00 


2.80 


9.25 


2.73 


9.50 


2.67 


9.75 


2.61 



TABLE X. 

COMPOSITION OF AGRICULTURAL MATERIALS AND PROD- 
UCTS IN 1000 PARTS OF THE SUBSTANCE. 



From this Tabic the student may gam some idea of the 
chemical composition of the more important substances 
relating to agriculture; although since this composition 
varies so widely with varying circumstances, no great 
degree of precision can be claimed, for statements of so 
general cliaraci;er, with whatever care they may be pre- 
pared. 

The extreme and the average composition are given ; 
the latter is to be taken, however, as indicating not the 
real mean of all the reliable analyses of the substance 
that have been made, but rather as an approximation to 
the proportion of each clement or compound that is gen- 
erally found in the substance ; in some cases the propor- 
tion of a component ranged too evenly from one limit to 
the other of the extremes to admit of estimating any 
average of this kind. Fuller details may in some cases 
be found in the admii-ably arranged tables at the end of 
Prof. Johnson's " How Crops Grow." 
13 



290 



TABLES. 
TABLE X. 





d 


1^" 


d 


d 

i 


O 
g 


^ 


d 




i 

< 


i 




Ashes, coal 
(anthracite). 




22. 

87. 










14. 
57. 

23. 


2. 
30. 


350. 
430. 


52. 
130. 


437. 
545. 




50.* 


15. 


380. 


80. 


500. 


Ashes, coal 
(bituminous). 




15. 
147. 



25. 



23. 






10. 
230. 

30. 


7. 
14. 


225. 
350. 


23. 

258. 


269. 
024. 




70.* 






10. 


2!)3. 


60. 


481. 


Ashes, peat. 




20. 
220. 



200. 



95. 






10. 
580. 



160. 


10. 
170. 




730. 


10. 
700. 




70.* 


8. 


4. 


200. 


20. 


30. 






Ashes, wood. 




2.* 

28. 


2«. 
220. 


20. 
160. 

75 




15. 




270. 
500. 


16. 
245. 

70. 




6. 

80. 


5. 
00. 






115. 


380. 


29. 


32. 


Bone ash. 







2.5 


0.3 






510. 
550. 

530. 


8. 
14. 














10.6 


5.- 


10. 




Bone-black. 


30. 
40. 


58. 
880. 

800. 


1 


t 






275. 
430. 


5. 
9. 

8.5 


42. 
52. 




400. 


7. 


50. 


Bone meal. 


47. 
167. 

75. 


520. 
680. 

600. 


t 


t 






260. 
360. 


11.6 




5. 


2.8 
15.5 




325 


0.7 




10. 


Cement (hy- 
draulic). 






1. 
11.3. 

7. 



17. 






550. 
628. 

602. 



22. 


53. 
94. 


4.5. 
61. 


229. 
260. 




6.3 


10.4 


73. 


33. 


240. 


Cheese. 


95. 
520. 


5. 
67. 




6.(?) 


38. 




7. 


0.3 










380. 


43. 


2.5 




0.1 


(2) 
Clay. 




330. 

130. 





33. 




27. 

9. 







183. 




40. 


100. 
390. 



250. 


150. 

770. 




19. 


20. 


10. 


280. 


90. 


480. 


(3) 
Coprolites. 


20. 
100. 

35. 




3. 

58. 


5. 

7. 










10. 
50. 


460. 


15. 


20.- 
4( 


-60. 
). 




360. 


30. 


Excrements, 
solicl(Herbiv). 


565. 
906. 


11. 

58.7 


0.77 
4.8 


0.26 
1.9 


0.009 
0.08 




1.4 

10.7 


1. 
3. 




0.43 
1.4. 


16. 
29.4 




764. 


25. 


3. 


0.9 


0.05 


4.6 


2.5 


1.0 


21. 


Excrements, 
solid (Man). 


708. 
S30. 

800. 


22. 
34. 

28. 


2.5 


1.4 
2. 


0.18 
1.2 

0.6 




5.8 

7.2 

6.4 


2.9 
3.6 




0.6. 


1.9 
2.4 




1.67 


3.2 


2.1 



* In 1000 parts of the fuel.— T Possibly present. 
33; KoO and NasO usually 0.— (2) Mn, 0—0.3; 
Fluorine, 0—50 ; average 30. 



— (1) Fluorine 36 — 40, average 
K2O and NajO mostly 0.— (3) 



TABLES. 



291 



TABLE X.—iCojiiinued. 





i- 


o 




o 
o 


m 


d 


^" 




"3 ^ 




t 


Ashes, coal (an- 
thracite). 





tr. 




















Ashes, coal 
(bitiimiuous). 


0. 

84. 


0. 
66. 






















50. 


10. 




Ashes, peat. 


0. 
370. 


0. 

80. 





306. 





65. 

10. 














50. 


30. 






Ashes, wood. 


7.S 
57. 

4. 


18. 

48. 

50. 








t 












Bone ash. 


tr. 


380. 
400. 




14. 
40. 

30. 


















390. 




Bone-black. 


40. 


100. 
380. 

300. 




15. 

27. 






5. 
32. 

7. 












17. 




Bone meal. 




180. 
280. 




60. 






28. 
50. 

38. 


^ 






1 




220. 






Cement (.hy- 
draulic). 


0. 
18.8 

10.2 






















Cheese. 




11.5 








t 


t 


80. 
440. 

240. 






100. 
600. 

310. 


Clay. 
























Coprolites. 


7.6 
10.6 


30. 

380. 




1. 
67. 




traces 



25. 












9.0 


230. 


30. 




Excrements, 
solid (Herbiv). 


0.47 

1.5S 

0.87 


2.2 

5.5 






t 


t 


2.2 
9.0 


17. 
23. 


86. 
110. 


80. 
110. 


10. 
13. 




3.6 


4.7 


20. 


95. 


95. 


10. 


Excrements, 
solid (Man). 


0.3 
0.9 


8.5 
10.9 






t 


t 


4. 


t 

1 


' t 


t 


t 




0.6. 


1 9.9 





t Present.— 1 Possibly present. 



292 



TABLES. 

TABLE X.— [Continued. 





d 






d 


rt 


S 


t 


d 


< 


O 


O 


Flesh. 


446. 
590. 


10. 
37. 


4.1 
5.2 




1. 






0.2 
0.8 


0.2 
0.5 






0.1 
0.3 




5^. 


22. 


4.5 


0.7 


0.3 


0.4 


0.2 


Fodder, dry, 
graminaceye. 


118. 
180. 


24. 
111. 








? 








0.13 
0.4 






150. 


66. 


17.1 


4.7 


7 7 


3.3 


0.2 


19.7 


Fodder, dry, 
legamiuosffi. 


IIG. 
200. 


45. 

80. 


10.6 
19.5 




4.7 




? 


15. 

31. 


2.6 

7.0 




0.3 
1.7 


0.6 
2.7 




160. 


70. 


15.8 


1.5 


19. 


5.0 


0.36 


1.5 


Fodder,L,'reen, 
gramiuacece. 


690. 
870. 


7. 
21. 


5.3 
11.6 


0.1 
1.6 




1 


0.7 

2.7 

1.5 


0.3 
1.9 

0.7 




+ 


2.1 
12.3 




745. 


18. 


7. 


0.5 


7.3 


F<)dder,i>;reeii, 
k'guminosse. 


740. 
850. 


10. 
20. 


1.0 
6.6 



1.1 





2.6 * 


3.0 

8.5 


0.6 
1.6 




t 


0.1 
0.6 




804 r 


12. 


1.5 


0.4 




4.9 


1.0 


0.4 


Fruits. 


760. 
880. 


2. 
9. 


1.0 
2.4 




0.7 






0.1 
0.4 

0.3 


0.2 




0.08 
0.33 






820. 


4. 


2.0 


0.3 


0.19 




Guano, 
ammouiacal. 


100. 
200. 

140. 


330. 
400. 


16.0 
30.0 

20.0 


12. 
35. 




62. 

100. 












344. 




12. 


8. 


12. 


Guano, 
phosphatic. 


10. 
140. 

100. 


7S0. 
950. 



12.0 




39. 






330. 
498. 



21. 


4. 
89. 



54. 



13. 


890. 


2.5 


6. 


400. 


2. 


1 3.7 




Gypsum. 


188. 
205. 

197. 












■im. 

325. 


tr. 




tr. 
50. 




309. 




Limestone. 


3. 
21. 




0.03 
1.12 



0.7 






410. 
550. 

500. 


3.4 
15.0 

8. 


^2. — 40."" 


1.7 
10. 




0.2 








Manure, fresh 
farm-yard. 


66U. 
710. 


34. 

78. 


1.2 
12.0 


0.2 

2.S 






2. 
15. 


0.5 

1.7 


^ 


7.5 
18.0 


1.7— 8. 




630. 


58. 


8.0 


1.2 


11. 


1.0 


3. 


14.0 


Manure,rotted 
farm-yard. 


750. 
790. 


70. 
73. 




0.6 
0.8 






10. 
19. 

15 


1.8 
3.8 




17. 
23. 






770. 


72. 


5.0 


0.7 


1.6 


6.7 


22. 


Marl. 


13. 

100. 

30. 




tr. 
14.8 

1.0 


tr. 
15. 





0.99 


2. 

520. 


3. 

220. 


"^.—90."' 












50 





* In the dry substance. + Present. 1^ Possibly present. (1) Free acid, esti- 
mated as malic acid, 1.0— 20.0; average 8.6. — (2) Oxalic acid, 58— 80 ; average 60. 
Vt\c acid present.— (3) Fluorine, traces. Sand S— 47 — (4) Insoluble silicates 
and sand, 50— 1'50. 



TABLES. 



293 







TABLE 


X.— [Continued. 














CO 




O 


O 
o 


C/2 


O 


^ 


§1 


6a 






Flesh. 



0.4 


4.3 

5.8 






t 


0.1 

0.7 


t 


123. 
174. 

144. 






210. 
397. 






5.0 


1 


0.4 


299. 


Fodder, drj% 
graminacece. 




3.3 


t 




1.7 
3.3 




t 


30. 

180. 

90. 


170. 
400. 

260. 


225. 
514. 

410. 


12. 
56. 




3.4 


4.1 


2.5 


5.3 


28. 


Fodder, dry, 
leguminostE. 


1.5 
5.3 


4.7 
9.0 



0.031 




0.9 
2.7 

1.8 


1.3 
2.1 

1.5 


+ 


7-> 
190.' 


190. 
400. 


150. 
480. 


12. 
55. 




2.8 


6.5. 


140. 


•280. 


330. 


30. 


Fodder, jjreeu, 
graminacese. 


0.2 

1.2 


1.3 
2.4 


tr. 




0.3 

0.8 


0.4 
1.9 


t 


17. 

CO. 


30. 
170. 


35. 
230. 


3. 

15. 




0.7 


1.7 


0.5 


1.0 


30. 


90. 


129. 


10. 


Fodder, green, 
leguminosae. 


0.2 
2.2 


0.9 
2.0 

1.4 


0.007 
5.0 




0.3 
0.8 


0.2 
1.0 


t 


72." 
28. 


30. 
160. 

60. 


50. 
140. 


4. 
9. 




0.8 




0.5 


0.4 


75. 


6. 


Fruits, 




0.4 

0.7 

0.5 








0.1 
0.4 


+ 


3.2 

8.0 

5.0 


28. 
117. 

49. 


14. 

120. 
* 

64. 






0.2 


Q.l 


0.2 




Giiauo, 
ammoniacal. 




00. 
137. 










80. 
170. 

110. 












T. 


100. 




Guano, 
phosphatic. 





170. 
420. 



5. 



15. 






8. 


tr. 
40. 












6. 


340. 


3.2 


1.5 






Gypsum. 


118. 
100. 






tr. 
30. 


















140. 






Limestone. 


0.3 

0.7 


0.03 
12.0 




310. 
140. 




0.32 

1.7G 



1.6 












2.0 


O.S 


400. 




Manure, fresti 
farm-yard. 


1.0 
3.0 


1 2 
3.0 






t 


0.0 
2.0 


4.0 

7.4 


t 


t 


t 


t 


1 


2.0 1 


2.8 


0.8 


fi.O 




Manure, rotted 
farm-yard. 


1.2 
2.4 


3.4 

4.5 


t 






0.2 
1.6 


6.0 












3.9 


0.9 






Marl. 


tr. 
15. 


tr. 
5. 




30. 
450. 




tr. 




















1 





* Sugar.— t Present.—^ Possibly present. 



294 



TABLES. 









TABLE 


X.—[Conilnued. 














1^- 


d 


d 

i 


1 


^ 


d 
o 


d 

s 


o 
< 


4! 

J" 




Milk. 


860. 
875. 


7. 
8.5 




0.7 








0.2 








870. 


7.3 


1.7 


1.5 




(1) 
Phosphorite 
(Apatite). 


4. 
25. 





12.0 



5.0 




200. 
550. 



2.3 





66. 


0.37—90. 


15. 




5.6 


3.0 




440. 


1.8 




50. 


Plants, cereal; 
grain. 


1^6. 
148. 


7. 
39. 


3.3 
5.5 


0.2 
1.0 




tr. 
3.4 


0.14 
10. 


1.8 
2.2 





0.6 


0.3 
12. 




142. 


20 


4.6 


0.5 




0.6 


1.9 




0.18 




Plants, cereal: 
straw. 


90. 
225. 


40. 
56 


4.9 
16.6 



3.5 




tr. 
1.5 


2.3 
5.0 


0.4 
2.6 




.02 
2.11 


18. 
34. 




150. 


45. 


6.0 


2.5 




3.6 


1.4 


1.0 


25. 


Plants, com- 
mercial. 
(Hops, tobac- 
co, etc.) 


100. 
300. 


28. 
198 


5.2 
54.1 


0.9 

7.3 




1 


5. 
73. 


2.0 
20.7 




.08 
3.0 


0.8 
19. 


220. 


50. 


15.0 


1.6 


8. 


3.0 


1.74 




Plants, 
le^nmc ; 
Bceds. 


128. 
148. 


17. 
35. 


6.3 
12.0 


0.4 
6.0 




1 


0.6 

2.7 


0.4 
2.1 






0.48 


0.2 
0.4 


144. 


25. 


9.8 


1.0 


1.5 


1.7 


0.15 


0.3 


Plants, 
]c!?ume ; 
straw. 


100. 
190. 


38. 
584. 


9.7 
25.9 


1.1 
3.9 




t 


9.5 
25. 


1.9 
4.G 




0.09 
0.2 


2.4 
3.1 


150 


50. 


18.9 


2.6 


15. 


3.0 


0.13 


2.7 


Potatoes ; 
tubers. 


(50. 
800. 


5.6 
46. 


5.6 
6.7 


0.1 
0.4 




^ 


0.2 
0.4 


0.3 
0.4 

0.35 




0.04 
0.06 


0.2 




775. 


10. 


6.1 


0.25 


0.2;-) 


0.05 




Potatoes ; 
tops. 


770 
820. 


11. 
16. 


0.7 
2.3 


1 




■ 1 


5.1 
5.5 


2.6 
2.7 




0.21 


0.5 

8.5 




797. 


14. 


1.5 




5.3 


2.65 




Root-crops ; 
roots. 


754. 

920. 


6. 

10. 


1.9 

4.3 


0.8 
2.0 




1 


0.4 
0.9 


0.1 

0.7 




0.01 
0.29 


0.1 
0.3 




875, 


8. 


3.5 


1.0 


0.7 


0.4 


0.09 


0.2 


Hoot-crops ; 
tops. 


705 
920. 


15. 
33. 


3.2 
6.0 


0.5 
6.0 




t 


1.7 
8.6 


0.4 
3.3 




0.15 
0.28 


0.1 
2.6 




85 


17. 


4.1 


1.5 


4.8 


1.3 


26- 


1.0 


(2) 
Salt. 


12. 
63. 


937. 

988. 




2.3 


t 


890. 
994. 




1.15 

9.7 


0.2 

2.8 




tr. 



tr. 


53.0 




34. 


963. 


2.2 


975. 


8.0 


1.7 








Saltpetre 
(Chili). 


1. 
20. 




1 


330. 
358. 


















10. 


980. 


340. 


1.0 


1.0 


29.0 



t Present.— t Possibly present.— (1) Fluorine 0—49; average 28.— (2) NjOj 
usually 0. 



TABLES. 



295 







TABLE 


'K..— {Continued. 




















i 


02 


3 


^ 


3 oj 




y 53 c 


i 


Milk. 










0.7 




24. 

68. 

38. 




29. 
83. 


22. 
60. 




0.1 


1.9 


47.* 


35. 


Phosphorite. 
(Apatite). 


tr. 


300.0 
4G0.0 




3.0 
43.0 




0. 
5.0 
















360.0 


25.0 






Plants, cereal ; 
grain. 


0.1 
0.5 


5.5 
10.0 


tr. 
6.8 




0.4 
1.7 


0.18 
0.27 


19. 
42.5 


526. 
270. 


7. 
165. 


500. 
765. 


5. 
70. 




0.36 


8.0 




1.0 


0.2 


20.0 


120. 


60. 


640. 




Plants, cereal ; 
straw. 


0.9 
2.5 


1.4 

3.8 



5.2 




0.9 
4.0 


1.2 
1.3 


1.7 
4.2 


6. 
100. 


290. 
550. 


ISO. 
455. 


6. 
25. 




1.4 


2.5 




2.0 




3.0 


37. 


460. 


300. 


13. 


Plants, commer- 
cial. (Hops, to- 
bacco, etc.) 


0.8 

7.7 


3.3 
9.0 


1 





4.8 


0.7 

8.8 


+ 


55. 






43 


2.0 


7.1 


3.4 


1.8 


672. 




Plants, legume ; 
seeds. 



2.3 


5.2 
S.l 



tr. 





2.5 


0.2 
0.6 


t 


200. 
350. 


37. 
145. 


270. 
600. 


12. 
76. 




1.3 


8.0 


2.4 


0.5 


250. 


97. 


400. 


32. 


Plants, legume ; 
straw. 


0.1 

2.8 


2.7 
6.1 


ir 




0.7 
2.2 

1.5 


2.7 
8.1 


5. 

18. 


48. 
100. 


250. 
530. 


170. 
400. 


10. 
50. 




2.0 


3.8 


4.5 


9. 


80. 


390. 


300. 


18. 


Potatoes; tubers. 


0.3 
0.6 


1.6 
2.0 


1 




0.2 
0.94 

0.9 


t 


0.8 
3.0 


5. 
40. 


3. 

27. 


120. 
160. 


0.5 
8.0 




0.45 


1.7 


2.0 


18. 


10. 


190. 


3.0 


Potatoes; tops. 


0.0 
0.9 


0.6 
1.0 


0.78 




0.5 
0.6 


0.4 
0.7 




t 


t 


+^* 


t 




0.75 


o.s 




0.55 


0.55 


5.5 




Itoot-crops • 
roots. 


0.3 
1.1 


0.5 
1.4 


0.12 
3.6 





4.4 


0.1 
2.5 


t 


5. 
26. 

11. 


3. 
45. 

12. 


23. 
155. 

85. 


0.8 
8.0 




0.6 


1.0 


0.67 


3.9 


0.33 


1.0 


Koot-crops ; 
tops. 


1.1 
3.0 


0.8 

2.0 


1 




0.5 
1.4 

O.G 


0.3 
10. 


8. 


12. 

38. 


9. 
34. 


21. 
129. 


3. 

10. 




1.7 


1.5 






26. 


25. 


60. 


6. 


Salt. 


1.4 
10.6 

6.0 






tr. 






0.5 
3.7 

1.9 












Saltpetre 
(Chili). 






571. 
620. 




















TO. 


.596. 


8.0 


170 





* Sugar.— t Present.—^ Possibly present. 



296 



TABLES. 

TABLE X.— [Continued. 





9, 


Il 


& 


d 

i 


1 


S 


§ 


1 


O 

< 


i 


O 
(2 


(t) 

Soils. 




920. 
990. 


tr. 

28. 


tr. 
20.7 




0.0023 
0.102 


tr. 
170. 


tr. 
14.0 


8 
140. 


15. 
110. 


t 




950. 


4.0 


2.0 


0.0485 


5.0 


3.0 


50. 


30. 




Sugar-beet. 


800. 
900. 


3. 
6. 


2.5 
3.5 


0.15 
0.3 


0.4 
0.9 


t 


0.4 
0.7 


0.16 
0.21 




0.1 
0.2 






815. 


5. 


3.0 


0.2 


0.7 


0.5 


0.2 


0.12 


0.1 


Superphos- 
phate. 


94. 
•2-23. 

155. 


576. 

728. 

665. 


1 


^ 






159. 
325. 




22. 





3.0 




230. 


1.0 






(3) 
Urine. 
Herbivora. 


8(50. 
925 


17. 
47. 


6.0 
20. 


2.0 
5.0 


t 




0.31 
0.16 










875. 


30. 


13. 


3.0 


4.2 




Lrine. 
Man. 


934. 

970. 

948. 


10.3 
14.5 


1.7 
5.0 


1.0 
3.0 


3.6 
8.0 



0.9 



0.33 



0.23 








13.5 


2.5 


2.0 


6.0 




0.26 


0.2 




Water, rain. 







tr. 



tr. 




0.0001 
3.004 

).0014 



tr. 



tr. 




J 
tr. 


3 

tr. 


(5) 
Water, river. 







0.013 



0.024 




0.00009 
0.005 


0.007 
0.1 


0.002 
0.032 




0.007 



0.012 


0*001 
0.013 






0.001 


0.061 


0.01 




0.006 




Water, spring. 






10 
0.41 0.58 





0.0006 


0.002 
0.23 



0.104 



0.0128 


') 
3.0045 



0.14 






1 




0.02 











t Present.— 1 Possibly present. — (1) Mn, traces to 17 ; average 0.8. SiOa and 
insoluble silicates 240—930; average 770.— (2) Fe203, tisually traces. Sand and 
insoluble silicates 29—178; average 48. Soluble P2O5 in older and foreign phos- 
phates, 120 ; in recent American. 33. Chlorine, usually 0.— (3) Hippuric acid, 
1.8—60. Urea, 18—70: average 28.— (4) Urea, 23—33; average 29. Uric acid, 
0.5-1.1; average 1.— (5) Mn. 0—0.003.— (6) AI2O3, NH3, FesOg, P2O5, and N0O5 
usually 0. MgO, KjO, NaaO, SO3, CO2, and CI, rarely 0. Organic matter 0—0.07 ; 
average 0.03. 



TABLES. 



297 



TABLE X.—[Con(inu€d. 





i 


i 


o 


O 
o 


ca 


o 


^ 


<1 


§1 


sis 


i 


Soils. 


0.07 
11.0 


0.001 
5.00 


O.OOl! 
0.12 220. 





14. 


0.5 

50. 












1.5 


1.0 


0.03 


5. 


0.3 


2. 




SuLjar-beet. 


0.18 
0.28 


0.37 
1.0 


0.3 
1.7 




t 


t 


t 


6. 

28. 

8. 


10. 
34. 

13. 


66. 
138. 

* 

100. 


6. 
9. 




0.2 


0.7 


1.0 


0.1 


8. 


Superphosphate. 


121. 
314. 


126. 
233. 









59. 


3.9 
27. 












210. 


170. 




20. 




Urine. 
Herbivora, 



1.6 






8.7 
14.0 

10.8 





3.3 


4.4 
26. 














15. 


1 




Uriue. 
Man. 


0.4 
3.7 

1.5 


1.7 
3.0 

2.0 








2.0 
5.0 


7. 
18. 












3.6. 


14.5 




Water, rain. 


V. 


0. 
tr. 


0.0001 
0.006 




















0.0005 




Water, river. 


0.002 
0.079 




0.001 
0.01 


0.0017 
0.08 

0.046 





0.089. 














0.022 




0.01 




Water, spring. 



0.5 



0.006 



0.67 



0.970 





0.560 




















0.2 







* Sugar.— + Present. 



INDEX. 



Acetic acid, as reagent, 8 — estima- 
tion, 101— in vinegar, 208— oc- 
currence of, 145— reactions 101 

Acetometer 21 

Acids, free, in wine 280 

Albumen, 117— in millc 2(33 

Albuminoids, see protein com- 
pounds. 
Alcohol as reajjcnt, 10— estimation, 

126— in wine 270 

Alcoholometer 24 

Alkalies, elimination by milk of 
lime, 157— by oxalic acid, 158 — 
estimation as chlorides, 53, 157 
— as sulphates, 53 — in gypsum, 
238— in limestone, 209— in marl, 

207— in wine 2S3 

Alumina, hydrated, in soil 180 

Aluminium, elimination of, 153 — es- 
timation of, 60 — reactions 65 

Ammonia, estimation of by distilla- 
tion with sodic hydrate and ti- 
tration, 57 — by distillation and 
Nessler's solution, 58— platinic 
chloride, 55— Schliissing's proc- 
ess, 56— in beets, 260— in fodder, 
aqueous extract of, 254 — in gua- 
no, 232 — in manure of the 
farm-yard, 214— in soil, 183— in 
superphosphate, 235— in urine, 

219— in water 272 

Ammonia, reactions of. 54 

Amnionic acetate as reagent, car- 
bonate chloride, fluoride, 10 — 
hydrate molybdate, nitrate, oxa- 
late, sulphate, sulphide, 11 — 

tartrate 12 

Ammonio-ferrous sulphate, as re- 
agent 12 

Ammonium, see ammonia. 

Analyses, calculation of 42 

Analysis, qualitative, course of for 
acids, 130— for bases, 130— table 
for 144 



Analysis, quantitative, schemes for, 
101— special methods for separa- 
tion in 146 

Animal substances, ash of 248 

Aqua regia, as reagent 8 

Argentic nitrate as reagent, 12— 
standard solution of 95 

Arsenic, occurrence of, 145 — reac- 
tions 73 

Artichokes 202 

Ash analysis, preparation o-f ash 
foi", 241 — statement of results. . .247 

Ash, elimination of carbon and car- 
bonic acid in 150 

Ash of animal substances, 248 — of 
bone-black, 230— of bone-meal, 
228— of coal, 243— of flour, 202— 
of fodder, aqueous extract, 253 
—of green fodder, 251— of fuel, 
249— of guano, 232— of manure 
of the farm-yard, 213, 216— of 
milk, 203 — of peat, 243 — of 
plants, 241— of seeds, 202— of 
superphosphate, 235, 236 — of 
urine, 218, 219— of wine, 278— of 
wool 270 

Ash of plants, carbonic acid, chlo- 
rine, 243— coal, sand and silica, 243 

Ash of plants, Reichhardfs method 
of preparing, for estimation of 
sulphur and chlorine 246 

Asli rich in carbonates, 243 — rich in 
silica 244 

Ash, sulphur in 240 

Ashes of fuel, carbonic acid, chlo- 
rine in, complete analysis of, 
potassa in 249 

Baker guano 234 

Baric acetate as reagent, chloride 
hydrate, nitrate 13 

Barium, occurrence of, 145 — reac- 
tions 59 

Bark, tanner's, tannic acid,water in, 270 

Beets (and turnips), ammonia in, 



INDEX. 



299 



258— ash of, 2o&— crude cellulose 
in, fat, 258— nitric acid 2G0— ni- 
trogen, pectose, 258— starch 2G0 
—sugar, 258— water 257 

Bone-ash 231 

Bone-black, ash of, 230— calcic hy- 
drate in, carbonic acid, chlo- 
rine, nitrogen, phosphoric acid, 
etc., water 230 

Bone-meal, ash of, 228, 229— fat in, 
fineness of division, gelatine in, 
229— nitrogen, phosphoric acid, 
water 228 

Bunsen's method of filtration 33 

Butter (and cheese), casein in, fat, 
2G7— salt, 2G8— water 267 

Butter in milk, estimation of, 264, 
266— by Yogel's optical milk- 
test -65 

Calcic chloride as reagent, hydrate, 
fluoride, sulphate 14 

Calcic hydrate in bone-black 230 

Calcium, elimination of, 157— esti- 
mation of as carbonate by igni- 
tion of oxalate, 60— as lime by 
ignition of oxalate, 61 — as oxa- 
late by titration of oxalic acid, 
61— as oxalate in presence of 
phosphoric acid, 62— as sulphate 
by conversion of oxalate into 
sulphate, 62 — reactions, 60 — 
separation from magnesium 64 

Calculation of analyses 42 

Carbon eliminated from residue left 
after incineration, 150— in urine. 223 

Carbonic acid, estimation of, 79— 
by Fresenius's apparatus, 81 — 
in ash left in the determination 
of volatile matter, 150 — in ash 
of plants, 243, 244— in ashes of 
fuel, 249— in bone-black, 230— 
in gypsum, 238— in manure of 
the farm-yard, 213, 215— in marl, 
206— in soils, 173— in urine, 218 
—reactions of, 79 — separation 
from chlorine 83 

Casein, 118 — in butter and cheese, 
207- in milk 263, 266 

Cellulose, 108 — in excrements of 
animals, 223— in fodder, 252, 256 
—in seeds, etc., 262 — in roots, 
258— reactions 108 



Cement, hydraulic, analysis and 

testing of 211 

Cheese, (see also butter) 267 

Chili saltpetre, adulterations detect- 
ed, 240 — complete analysis of, 
239— nitric acid in, 240— potash, 

soda, water in 239 

Chlorine, estimation of by gravime- 
tric process, 94— by volumetric 
process, 95— in ash of fuel, 249 
—in ash of plants. 243, 244— in 
bone-black, 230 — in farm-yard 
manure, 215 — in organic combi- 
nation, 152— in the plant, 245— 
in soil, 186— in urine, 220— reac- 
tions of, 94— separation from 

carbonic acid 83 

Citric acid, as reagent, 8— occur- 
rence of, 145— reactions 103 

Clark's method of determining 

hardness of water 274 

Clay 212 

Coal (carbon) in ash of plants 243 

Coal ashes 250 

Cobaltic nitrate as reagent 15 

Cochineal as reagent 15 

Copper, occurrence, 145— I'eactions. 73 
Coprolites, complete analysis of— 

phosphoric acid in 231 

Cupric acetate as reagent, sulphate, 15 

Curcuma-paper 15 

Cyanogen, occurrence, 146 — reac- 
tions 97 

Desiccator, the 40 

Desiccation of substances 147 

Division of solutions in quantita- 
tive analysis 40 

Dragendorflf's process for estimat- 
ing starch HI 

Dung of animals 223 

Ether, as reagent 15 

Evaporation, 27— of solutions con- 
taining excess of amnionic salts, 
when the residue is to be ignit- 
ed 28 

Excrements, solid 223 

Fat, 125— in beets, 258— in bone- 
meal, 229 — in butter, 267 — in 
flour, 262— in fodder, 252— in 

milk, 264— in seeds 262 

Fehling's solution 113 

Ferric chloride as reagent, 15— ni- 



300 



INDEX. 



trate, oxide 15 

Ferric oxide, elimination, 153— esti- 
mation, G7 — hydrated, with 
alnminic hydrate in soil, 18G — 
and other substances in farm- 
yard manure, 216— reactions, 60 
—separation from phosphoric 

acid 153 

Ferrocyanogen, occurrence, 140 — 

reactions 98 

Ferrous chloride as reagent, 16— 

sulphide IG 

Ferrous oxide in soil, estimation, 

187— reactions 66 

Fertilizers, 213— commercial, tariff 

of prices for valuation of 220 

Fiber, see cellulose. 

Fibrine 118 

Filters, incineration of, 3S— wash- 
ing? of with dilute acid 31 

Filtration, 31— byBuusen's process, 
33— by the wash-bottle arrange- 
ment 37 

Fleck's method of determining 

hardness of water 270 

Flour, (see also seeds) 262 

Fluorine, reactions On 

Foddei", aqueous extract of, estima- 
tion, 253 — ammonia in, 254 — ash 
of, 253— gum, nitric acid in, 255 

—nitrogen, 254— sugar 255 

Fodder, dried, 251— ash, 251— cellu- 
lose in, fat, protein compounds, 

252— starch, 257~water 251 

Fodder, green, ash of, water in, 
preparation of sample for analy- 
sis 251 

Gelatine in bone-meal 229 

Glucose, estimation, reactions 113 

Graduated instruments, testing and 

use of 40 

Guano, ammoniacal (Peruvian), ash 
of, and ammonia in, 232 — com- 
plete analysis of, 233 — marks of 
a good article, 233— nitrogen in, 
232— oxalic acid, 233— phosphor- 
ic acid, etc., 232— solubility in 
water, 233— uric acid in, 233— 

water in 232 

Guano, phosphatic (Baker, etc.) 234 

Gum, estimation of, 112 — in fodder, 
aqueous extract of, 255 — in 



wine , 279 

Gypsum, alkalies in, and carbonic 
acid, 238— complete analysis of, 
237— solubility in acid, water 

in 237 

Heat, absorbent power of soil for, 
and conducting power, 197— re- 
taining power 193 

Hippuiic acid, estimation, reac- 
tions, separation from uric, 106 

— in urine 221 

Hops, statement of analysis of ash 

of 243 

Ilumus in marl, 208— in soil. ! 183 

Ilydric disodic phosphate as re- 
agent , 21 

Ilydriodic acid, reactions of 98 

Hydrochloric acid as reagent, 8 — es- 
timation, see chlorine — reac- 
tions 94 

Hydrocyanic acid 97 

Hydroferrocyanic acid 98 

Hydrofluoric acid 99 

Hydrogen as reagent, 16— in urine, 223 
Hydrosulphuric acid as reagent, 8— 
estimation, see sulphur — I'cac- 

tions 98 

Hj-groscopic moisture, estimation . .147 
Ignition of precirJktates, 38 — of resi- 
dues containing excess of am- 
nionic salts 28 

Incineration of filters, 33— to deter- 
mine organic matter 149 

Indigo solution as reagent 16 

Iodine as reagent, 16 — occurrence, 

146— reactions 98 

Iron (sec also ferric oxide), estima- 
tion by precipitation, 67 — by 
volumetric process with potas- 
sic permanganate, 67— by volu- 
metric process with sodic hypo- 
sulphite, 70 — reactions, GO — 
separation from alumina and 

phosphoric acid 153 

Iron turnings as reagent, 10— wire.. 16 
Lactic acid, estimation, 105 — occur- 
rence, 145— reactions 104 

Lactometer 24 

Lacto-protein in milk 2GG 

Lactose, 117— in milk 200 

Lead, occurrence, 146 — reactions... 72 
Lead-paper as I'eagent 16 



IXDEX. 



m 



Levigation 2G 

Levulose 115 

Lime, burned 209 

Lime in marl, 20G— in water, 2T3— 
reactions and estimation, see 

calcium 

Limestone, 209— alkalies in, 209— 
value for mortar lime, 210 — for 

hydraulic cement 211 

Litmus-paper, blue and red IG 

Magnesia (calcined) as reagent, 17 

— magnesia mixture IT 

Magnesium, elimination from mix- 
ture of metals, etc., 15T— esti- 
mation as pyrophosphate, 63— 
reactions, 02 — separation from 
calcium as pyrophosphate, 6-1 — 

by sulphuric acid 05 

Malic acid, estimation, 104 — in 
wine, 2S2— occurrence, 145— re- 
actions 104 

Malt, as reagent 17 

Manganese, elimination from mix- 
ture of substances, 15G — estima- 
tion, 71— occurrence, 140— reac- 
tions 71 

Manganic binoxide as reagent 17 

Manures, commercial, general con- 
siderations, 224 — nitrogen in, 
225— phosphoric acid, 224— po- 
tassa, 225 — statement of analy- 
sis, illustrated, 225 — tariff of 

prices for valuation of. 22G 

Manure of the farm-yard, 213 — am- 
monia in, 214— aqueous extract 
of, 214— ash, carbonic acid, 213 
— insoluble part, 214, 210 — nitro- 
gen, organic matter, 213— state- 
ment of analysis, illustrated, 
217— sulphur, sulphuric acid in, 

214— water 213 

Marl, alkalies in, 207 — carbonic 
acid, 200- humus, 208— lime and 
magnesia, 207— nitrogen, 208 — 
phosphoric acid, 207— silt analy- 
sis of, 205— water 200 

Marl, burned 208 

Meal (see also seeds) 202 

Measurement of solutions 40 

Mercuric nitrate as reagent, 17— 

standard solution of. 122 

Mercurous nitrate as reagent . . . .17 



Milk, albumen in, ash, casein, SOS- 
fat, 204, 205— lacto-protcin, etc., 
260— protein compounds, 2G3— 
sugar (lactose) 200— Vogel's op- 
tical test, 205— water 203 

Milk of lime as reagent 17 

Ncssler's solution as reagent, 55— 

estimation of ammonia with. . . 58 
Nitric acid as reagent, 8- estima- 
tion of by fusion of nitrate with 
silica, 92— by insolubility of am- 
nionic nitrate in alcohol, 93 — 
by Schlussing's process, 89— in 
beets 200— in Chili saltpetre, 
240— in farm-yard manure, 215— 
in fodder aqueous extract, 255— 

in soil 185 

Nitric acid, reactions 88 

Nitrogen in beets, 258 — in bone- 
black, 230— in bone-meal, 228— 
in commercial manures, 225 — 
in fodder, 252, 254— in guano, 
232 — in manure of the farm- 
yard, 213,215, 216— in marl, 208— 
in soil, 173 — in superphosphate, 

235— in urine 219 

Nitro-hydrochloric acid, see aqua 

regia 

Nitrous acid in water 273 

Organic matter, estimation by igni- 
tion in muffle, 149— ignition in 
platinum dish, 149 — by titration 
with potassic permanganate, 
151 — in manure of the farm-yard, 
213, 215— in soil, 183- in urine, 

218— in water 272 

Oxalic acid as reagent, 9— estima- 
tion by conversion into carbon- 
ic acid, 101— by titration with 
potassic permanganate, 100— in 
guano, 233 — reactions of, 99 — 

standard solution of 50 

Oxygen, preparation of 17 

Pea, as fodder plant, statement of 

analysis of 257 

Peat ashes 250 

Pectose in beets 258 

Peruvian guano 232 

Phosphate, see superphosphate 

Phosphatic guano 234 

Phosphoric acid, S3— elimination by 
ammouic molybdatc, 85, 157— by 



302 



INDEX. 



ferric chloride, soclic acetate, 
magnesia mixture, and citric 
acid, 159— by metallic tin, 155 — 
in presence of large excess of 
ferric oxide, IGO— when it alone 
is to be estimated, 159— estima- 
tion as magnesic pyrophosphate 
84 — by volumetric process, 
86— in bone-black, 230 — in bone- 
meal, 228- in commercial ma- 
nures, 224— in coprolites, 231 — 
in guano, 232 — in marl, 207 — in 
phosphorite, 231— in superphos- 
phate, insoluble, 23G— soluble, 

235— in urine 222 

Phosphoric acid, I'cactions of. 83 

Phosphorite, complete analysis of, 

231— phosphoric acid in 231 

Phosphorus salt, as reagent IS 

Piknometer 23 

Plant ash, see ash of plants 

Plant, chlorine in, 245, 24() — sulphur- 
ic acid (ready formed), 245 — to- 
tal sulphur 245, 246 

Platinum crucibles, care of. 40 

Platinic chloride, as reagent 18 

Plumbic acetate, as reagent, binox- 

ide, oxide 18 

Potash compounds, commercial 239 

Potassic acetate as reagent, 18— bi- 
sulphate, chromate, chlorate, 
dichromate, ferricyanide, ferro- 
cyanide, hydrate, iodide, per- 
manganate, 19 — and sodic car- 
bonate, and sodic tartrate, 

sulphocyanate 20 

Potassium, eliminatipn from mix- 
ture of metals by milk of lime, 
157- by oxalic acid, 158 — by 
platinic chloride, 159— from sili- 
cates, 16- estimation as chlor- 
ide, 45 — as potassic platinic 
chloride, 46— sulphate, 46— by 
titration with standard acid, 47 
—in ashes of fuel, 249— in Chili 
saltpetre, 239 — in commercial 

manures, 235— in water 272 

Potassium, reactions, 44 — separa- 
tion from sodium by indirect 
determination as chloride, 53— 
as sulphate, 53 — by platinic 
chloride 52 



Potassium and sodium, conversion 
of mixed sulphates into chlor- 
ides 53 

Potatoes, dry substance in, soluble 
in watei', protein compounds in, 

261— starch, 262— water 261 

Precipitation 29 

Precipitates, ignition of, with filter, 
38 — after separation from filter, 
38— transferring of to filter, 30— 

washing of, 32— weighing of 38 

Protein compounds, estimation of, 
118— in fodder, 252— in milk, 263 
—in potatoes, 2G1— in seeds, 262 

— in wine, 278 — reactions of 117 

Qualitative analysis, course of 130 

Quantitative analysis, schemes of... 161 

Quartz powdered, as reagent 20 

Eesidues, ignition and weighing of, 38 
Results of analyses, calculation of. . 42 
Rocks, and products of their weath- 
ering 205 

Saccharose, estimation, 116 — reac- 
tions 115 

Saccharometer 24 

Salt, complete analysis of, 238— esti- 
mation of in butter and cheese.. 268 
Saltpetre, Chili, see Chili saltpetre. 
Sand in ash of plants, 243— in soils, 

182— separation of from silica.. 75 
Schlossing's process for estimating 

ammonia, 56— nitric acid 89 

Seeds, ash, etc., dry substance solu- 
ble in water, in starch, water.. .262 

Silica and sand in ashes 243 

Silicates, fusion of with sodic and 
potassic carbonate, 76 — solution 
of, 74 -treatment of with ammo- 
nic fluoride, 77— with hydroflu- 
oric acid 77 

Silicic acid, estimations and reac- 
tions, 74— separation of from 

coal and from sand 75 

Silt analysis of marl, 205— of soils, 
Dietrich's method, 172— Nobel's 

method 169 

Silver refuse, to work over 12 

Skin, powder of. as reagent 118 

Soda-lime as reagent 20 

Soda, standard solution of 50 

Sodic acetate as reagent, 20— sodic 
and ammonic phosphate, 20— bi- 



INDEX. 



303 



Bulphite, carbonate, hyposul- 
phite phosphate, nitrate 21 

Sodium, elimination of from sili- 
cates, 76— elimination with milk 
of lime, 157 — with oxalic acid, 
15S — estimation of as chloride, 
or as sulphate, 52— by indirect 
processes, 53 — in Chili saltpetre, 239 

Sodium, reactions, 51— separation 
from potassium by indirect meth- 
od, as chloride or as sulphate, 53 
— by platinic chloride 52 

Sodium, sulphate of converted into 
chloride 53 

Soil, absolute weight of, 198— ab- 
sorptive power of for salts, 188 — 
adhesive power of 200 

Soil analysis, experiments to be 
combined with, 200 — general 
considerations in regard to, 105 
— preparation of sample for 166 

Soil analysis, chemical part, prepa- 
ration of soluticms for, 174— 
with carbonated Avater, 177— 
with cold hydrochloric acid, 174 
— with hot hydrochloric acid, 
179— with hydrofluoric acid, 181 
— with phosphoric acid, 182— 
with sulphuric acid 180 

Soil analysis, mechanical part, 168— 
silt process by Dietrich's meth- 
od, 172— by Niibers method, 109 

Soil analysis, physical part, in rela- 
tion to heat-absoi'bing power, 
197— to heat-conducting power, 
■ 197— to heat-retaining power, 198 
—consistency, 199— power of ab- 
sorbing water- vapor, 192 — of 
retaining liquid water, 193— of 
retaining water-vapor, 192— rate 
of evaporation of water from, 
194 — readiness with which 
water moves downward in, 197 
—readiness with which water 
moves upward, 196 — readiness 
with which water percolates 
through,196 — volume wiien com- 
pletely saturated with water, 199 
—porosity, 199— specific gravity, 
apparent and real, 198— tenacity,199 

Soil analysis, statement of results 
illustrated 188 



Soil, estimation of ammonia in, 188 
— of carbonic acid, 173— chlo- 
rine, 186- ferrous oxide, 187— 
hydrated alumina and ferric ox- 
ide, 186 — humus, 183 — nitrogen, 
total in, 173 — nitric acid, 185 — 
organic matter, 183— sand, by 
phosphoric acid, 182 — sulphur, 
186— water 173 

Solution 25 

Solutions, division and measure- 
ment of 40 

Solutions standard, preparations of, 
48, 55, 67, 70, SO, 95, 100, 113, 122, 
151,266 274 

Solutions, estimation of solid mat- 
ter in by simple evaporation on 
water-bath, 148— after mixture 
with gypsum, 149— by evapora- 
tion in vaccuo on hot sand, 148 
—to save ammonia that may be 
given off 148 

Specific gravity of liquids, with the 
areometer,23— with the piknome- 
ter or specific-gravity bottle, 23— 
of soil apparent and real, 198— 
of solids by specific gravity of 
liquid of the same density, 25 — 
if soluble in water, 25— by vol- 
unie of water disi)laced, 24— by 
weight of water displaced in 
piknometer, 24— of urine, 217— 
of wine, 278— of wool 270 

Starch, 109 — estimation by conver- 
sion into sugar by malt, 109— by 
sulphuric acid, 110 — Dragen- 
dorft's process, 111— in beets, 260 
—in fodder, 257— in potatoes, 
262— in seeds, 202— reactions of,109 

Stai-ch paper 21 

Sugar (see also saccharose, glucose, 
etc.) estimation in beets, 258 — 
in fodder, aqueous extract, 255 
—milk. 266, 207— in wine 279 

Sulphur, estimation in organic com- 
bination, 152 — in manure of the 
farm-yard, 214— in plant, total, 
245— in soil, 286— in urine, 223— 
reactions 93 

Sulphuric acid as reagent, 9— elimi- 
nation of, 157— estimation, 78— 
in gypsum, 237— in manure of 



304 



INDEX, 



the farm-yard, 214 — in plant, 245 
—in urine, 223— in vinegar, 208 
—in wine, 283- reactions of, 78 

— standard solution of 48 

Superphosphates, ammonia in 235— 
ash, 235— complete analysis of, 
236— nitrogen in, 235— phosphor- 
ic acid, insoluhle, 236— soluble, 

235— water 234 

Tables 284 

Tanner's bark 270 

Tannic acid, as reagent, 10 — estima- 
tion, 107 — in bark, 270— in wine. 
280— occuri-cnce, 145— reactions. 102 
Tin, as reagent, 21 — use to elimi- 
nate phosphoric acid 155 

Turmeric as reagent 21 

Uranic acetate as reagent, 21— stand- 
ard solution of 78 

Urea as reagent, 22— estimation, 122 

—in urine, 221— reactions 122 

Uric acid, estimation, 105— in guano, 
233— in urine, 221— reactions, 105 

—separation from hippuric 106 

Urine, ammonia in, 219— ash of, 218, 
219 — carbon in, 223 — carbonic 
acid, 218- chlorine, 220— dry sub- 
stance in solution, 218 — hippuric 
acid, 221— hydrogen, 223— nitro- 
gen, 219- phosphoricacid, 222— 
sulphur and sulphuric acid, 223 
—urea, 220— uric acid, 221— 

specific gravity of 217 

Valuation of manures 220 

Vinegar, acetic acid in, 208 — free 

sulphuric acid 208 

VogePs optical milk test 265 

Washing bottle 33 

Water distilled as reagent 22 

Water, hj'groscopic, estimation of 
by simple desiccation on the 
water-bath, 147 — estimation 
when ammonia is present, 147 — 



estimation by simple ignition, 
147— estimation ^of in bark, 270 
— in beets, 257 — in bone-black, 
230— bone-meal, 228— butter and 
cheese,267— Chili saltpetre, 239— 
fodder,251 — green parts of plants, 
241— gypsum, 237— guano, 232— 
marl, 200— milk, 263— potatoes, 
261— roots, 241— salt, 238— seeds, 
262— soil, 173— superphosphate, 
234— wool 270 

Water, estimation of ammonia in, 
272 — of dry substance in solution 
in, 271 — of hardness, Clark's 
method, 274 — hardness byFleck's 
method, 276— of lime in, 273— of 
nitric acid, 272— of nitrous acid, 
273— organic matter, 272 — the 
same by titration with potassic 
permanganate, 151— potassa in.. 272 

Water, expulsion of from solutions, 
see evaporation— relation of to 
soil in liquid form, 193— as va- 
por 192 

Wine, alcohol in, 279— alkalies in, 
283— ash of, 278- average com- 
position of, 283— dry substance 
in solution, 278— free acids in, 
280— gum and sugar, 279— malic 
acid, 282— protein compounds, 
278— specific gravity of, 278 — 
sugar, 279— sulphuric acid free, 
283— tannic acid, 280- tartaric 
acid 282 

Woltf s process for converting starch 
Into sugar Ill 

Wool, estimation of ash of, 270— of 
effect of washing at the factory, 
270— water in, 270— preparation 
of sample for examination 269 

Zinc as reagent, 22 — occurrence, 
146— reactions 72 



ADDENDA 

FROM PERIODICALS RECEIVED WHILE THE FOREGOING 
MATTER WAS IN PRESS. 

Bunsen's filtratiojj process; paj^e 33. R. S. Dale {Chem. News, 
Mig., Ed, 20, lOS) states, that more rapid filtration can be obtained by 
substituting platinum-wire gauze, for the foil in the funnel, without any 
more danger of tearing the paper; and the gauze funnel can be fitted in 
the glass one with sufficient accuracy, by means of a cone of wood turn- 
ed to the proper angle. Undoubtedly, this gauze funnel can be advan- 
tageously used in cases where the pressure on the liquid in the filter is 
much less than an atmosphere, as when the rarefaction of the air in the 
filtering flask is effected by means of the flow of water from one bottle 
to another. 

Standard acid and alkaline solutions; page 48. Dr. Fleischer 
{Chem. News ; Am. liepr., 5, 83) gives some good reasons for preferring 
a standard hydrochloric acid, instead of sulphuric; it forms soluble 
salts with all the alkaline earths, is readily obtained pure, is estimable 
with great accuracy by a standard solution of argentic nitrate as well as 
by an alkali, and its constancy is unimpeachable. The standard of the 
acid can be determined by means of a weighed amount of pure calcic 
carbonate, that has been slightly heated, or by the standard argentic so- 
lution. 

For a standard alkaline solution, ammonia has many advantages over 
soda; it is more easily obtained pure, and has so slight a tendency to 
absorb carbonic acid from the air, that no special provision need be made 
against it. 

As some neutral amnionic salts have a slight acid reaction when the 
solution is hot, the liquid to be tested should be cold. A solution con- 
taining half an equivalent of ammonia in the litre, is recommended. 

Both of these standard solutions should be kept in a cool place, free 
from dust. If tlieaniraonic solution is exposed to hot summer weather, 
the bottle containing it should be placed in cold water that is renewed 
every day; by exposure to a temperature above 25° C, the standard of 
the solution will be veiy slightly altered. 

Estimation of iron by the permanganate process ; page 67, M. 
Moyaux {Revue Universelle des ilfines, etc., Chem. News, Am. Repr., 5, 179) 
states, that the use of ammonio-ferrous sulphate to determine the staud- 
305 



306 ADDENDA. 

ard of the perraang-anic solution is unsafe, for the reason that the com- 
position of the salt is not constant, and that, consequently, metallic iron 
or oxalic acid must be used. Fresenius also, gives the preference to the 
use of metallic iron as the most accurate, although perhaps less conven- 
ient, method; he gives tlie following directions for executing the proc- 
ess. Weigh out about 0.2 grm. of the finest piano-forte wire, free from 
rust, and add to it in the long-necked flask (p. 68) 20 c.c. of dilute sul- 
phuric acid, and as much water, and proceed with the solution in the 
current of carbonic acid, and the subsequent titration, as directed in the 
case of the use of the ammouio-terrous sulphate. Instead of £, 

in tlie proportion on page 69, substitute F x 997 ; this product is taken 
as the weight of pure iron in the weight F of iron used, since the purest 
wire contains about 0.8" |o of impurities. 

In the text (pp. 69, 154) the preference is gfven to a sulphuric-acid so- 
lution of the ferious salt for titration rather than a solution in hydro- 
chloric acid. In an appendix to his Quantitative Analyse^ Fresenius states, 
tliat tlie titration of a hydrochloric-acid solution is unreliable unless con- 
ducted as follows. Make the volume of the solution up to a quarter of 
a litre, add 50 c.c. of this solution to a considerable quantity of water 
acidified with sulphuric acid, titrate this mixture with permanganate, 
add to it 50 c.c. more of the ferrous solution, titrate again, and so on 
witii a third and fourlh portion of the same solution; finally use the 
last two results, the mean of Avhich multiplied l)y five will give the 
amount of permanganic solution that should be required for the whole 
amount of the ferrous solution. 

The precipitate of ammonio-magnesic phosphate, in the esti- 
mation OF MAGNESIUM, PAGE 64, AND OF PHOSPHORIC ACID, PAGE 87. 

As the results of experiments by Kubel and by Kiesel {Fres. Zeitsdirift 
8, 2iP- 125, 164), it- appears that the solubility of this precipitate in the 
iiquid in which the precipitation takes place, in tlie presence of con- 
siderable amnionic chloride and a not too great excess of magnesic sul- 
ph:ite, is vei-y nearly compensated for by the minute quantity of basic 
magnesic sulphate, or of magnesia, that is precipitated at the same time; 
hence the correction for the imperfect insolubility of the precijutated 
phosphate seems to be unnecessaiy. 

Organic matter in w^ater, page 272. R. Angus Smith, who is a 
strong and earnest champion for the permanganate process, in the ex- 
amination of water with respect to the presence of hurtful organic 
matter, uses a stronger solution than Kubel (see page 151). He adds 2 
grms. of the salt to a litre of water, and gives the following directions 
for the titration : 

To not less than a litre of the water add a drop of this permnnganate 
solution ; stir the liquid well, and wait until the color disappears, and 
proceed in this manner as long as the color disappears quickly, say in a 
minute or two ; generally, considerable permanency of color is obtained 



ADDENDA. 307 

in 10-15 minutes. Then add 3 iirms. of sulphuric acid to the liquid aiul 
proceed to add more permanganate in the same manner as before. 

According to Dr. Smith, the oxygen of the permanganate used hefcn^e 
adding the acid, was taken np byproducts of putrefaction in solution in 
tliG water, such as sulphuretted In^drogen, and that required after the 
addition of the acid, was consumed b}' easily oxidizable organic (animal) 
matter; all matters tliatthus act speedily on the permanganate are the 
most harmful in a sanitary point of view. 

According to this writer and to W. A. Miller also, the results obtained 
can be expressed more accurately, by giving instead of the number of 
cubic centimetres of permanganic solution used, the amount of availa- 
ble oxygen therein — of wliich each cubic centimetre contains 0.005 
grm. 

Dr. Smith estimates the nitrous acid in the water roughly, by di- 
luting a measured quantity of it until iodized starch i)aper (paper 
dipped in a solution of potassic iodide containing a little starch) is 
no longer colored blue by it, even after a contact of several minutes; 
this diluted solution then contains about one pai't of nitrous acid in 
100,000 of water, and upon this basis the proportion in the water 
before dilution can be estimated. {Chem. News Am. Mepr. 5.141, Eny, 
Ed. 20.113). 



VALUABLE AND BEAUTIFUL WORK. 



HARRIS' 

Insects Injurious to Yegetation. 

BY THE LATE 

THiVDDEUS WILLIAM HARRIS, M.D. 

A New Edition, enlarged and improved, with additions from the anthor'i 
manuscripts and original notes. 
Illustrated by engravings drawn from nature under the supervision of 

PI^OT^ESSOR, ^G^ASSIZ. 

Edited by CHARLES L. FLINT, 
Secretary of the Massachusetts State Board of Agriculture. 

CHAPTER I. 

INTRODUCTION.— Insects Defined— Brain and Nerves— Air-Pipes and Breath- 
ing-Holes—Heart and Blood — Metamorphoses or Transformations- 
Classification ; Orders and Groups. 

CHAPTER II. 

COLEOPTERA.— Beetles— Scarabaeians— Ground-Beetles— Tree-Beetles— Cock- 
chafers— Flower, Stag, Spring, Timber, Capricorn, Leaf-mining, and Tor- 
toise Beetles— Chrysomelians—Cantharides. 

CHAPTER III. 

ORTHOPTERA.— Earwigs — Cockroaches- - Soothsayers — Walking-sticks or 
Spectres— Mole, Field, Climbing, and Wingless Crickets— Grasshoppers- 
Katydid — Locusts. 

CHAPTER IV. 

HEMIPTERA.— Bugs— Squash-Bug— Clinch-Bug— Plant Bugs-Harvest Flies— 
Tree-Hoppers— Vine-Hoppers — Plant-Lice— American Blight— Bark-Lice. 

CHAPTER V. 

LEPIOOPTERA.—Caterpillarg*—Butterfiies — Skippers — Hawk-Moths-^ge- 
rians or Boring Caterpillars— Moths— Cut-Worms— Span- Worms— Leaf- 
Rollers— Fruit, Bee, Corn, Clothes, and Feather- Winged Moths. 

CHAPTER VI. 

HYMENOPTERA.— Stingers and Piercers— Saw-Flies and Slugs— Elm, Fir, 
and Vine Saw-Fly — Rose-Bush and Peai--Tree Slugs — Horn-Tailed 
Wood-Wasps^Gall-Flies— Barley Insect and Joint Worm. 

CHAPTER VII. 

DIPTERA.- Gnats and Flies— Maggots and their Transformations— Gail 
Gnats— Hessian, Wheat, and Radish Flies— Two-Winged Gail-Flies, an*? 
Fruit-Flies. 
APPENDIX.— The Army Worm. 

Published in two beautiful editions ; one plain, with steel engravings, 8vo. 
•xtra cloth, $4 ; the other in extra cloth, beveled boards, red edges, engrav 
lugs colored with great accuracy, $6. 
Sent post-paid on receipt of price, 

ORANGE JUDD k CO.. 

245 Broadway New- York City 



3^77 



